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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
hep-ph/0508178
|
Matthias Neubert
|
Bjorn O. Lange (MIT), Matthias Neubert (Cornell & Heidelberg
University), and Gil Paz (Cornell University)
|
A two-loop relation between inclusive radiative and semileptonic B-decay
spectra
|
22 pages, 4 figures; few comments and one reference added; version to
appear in JHEP
|
JHEP 0510:084,2005
|
10.1088/1126-6708/2005/10/084
|
CLNS-05/1922, MIT-CTP-3668
|
hep-ph
| null |
A shape-function independent relation is derived between the partial
B->X_u+l+nu decay rate with a cut on P_+=E_X-P_X<Delta and a weighted integral
over the normalized B->X_s+gamma photon-energy spectrum. The leading-power
contribution to the weight function is calculated at next-to-next-to-leading
order in renormalization-group improved perturbation theory, including exact
two-loop matching corrections at the scale mu_i^2 ~ m_b*Lambda_{QCD}. The
overall normalization of the weight function is obtained up to yet unknown
corrections of order [alpha_s(m_b)]^2. Power corrections from phase-space
factors are included exactly, while the remaining subleading contributions are
included at first order in 1/m_b. At this level unavoidable hadronic
uncertainties enter, which are estimated in a conservative way. The combined
theoretical accuracy in the extraction of |V_{ub}| is at the level of 5% if a
value of Delta near the charm threshold can be achieved experimentally.
|
[
{
"created": "Tue, 16 Aug 2005 16:47:26 GMT",
"version": "v1"
},
{
"created": "Mon, 24 Oct 2005 09:32:21 GMT",
"version": "v2"
}
] |
2011-02-01
|
[
[
"Lange",
"Bjorn O.",
"",
"MIT"
],
[
"Neubert",
"Matthias",
"",
"Cornell & Heidelberg\n University"
],
[
"Paz",
"Gil",
"",
"Cornell University"
]
] |
A shape-function independent relation is derived between the partial B->X_u+l+nu decay rate with a cut on P_+=E_X-P_X<Delta and a weighted integral over the normalized B->X_s+gamma photon-energy spectrum. The leading-power contribution to the weight function is calculated at next-to-next-to-leading order in renormalization-group improved perturbation theory, including exact two-loop matching corrections at the scale mu_i^2 ~ m_b*Lambda_{QCD}. The overall normalization of the weight function is obtained up to yet unknown corrections of order [alpha_s(m_b)]^2. Power corrections from phase-space factors are included exactly, while the remaining subleading contributions are included at first order in 1/m_b. At this level unavoidable hadronic uncertainties enter, which are estimated in a conservative way. The combined theoretical accuracy in the extraction of |V_{ub}| is at the level of 5% if a value of Delta near the charm threshold can be achieved experimentally.
|
hep-ph/0011155
|
Bernd Andreas Kniehl
|
B.A. Kniehl, G. Kramer, B. Poetter
|
Testing the Universality of Fragmentation Functions
|
35 pages (Latex), 15 figures (Postscript)
|
Nucl.Phys.B597:337-369,2001
|
10.1016/S0550-3213(00)00744-6
|
DESY 00-158, MPI/PhT/2000-33
|
hep-ph hep-ex
| null |
Using fragmentation functions for charged pions, charged kaons, and
(anti)protons recently extracted from experimental data of e^+e^- annihilation
at the Z-boson resonance and at centre-of-mass energy root(s) = 29 GeV, we
perform a global study of inclusive charged-hadron production in p anti-p,
gamma p, and gamma gamma collisions at next-to-leading order in the parton
model of quantum chromodynamics. Comparisons of our results with p anti-p data
from CERN S p anti-p S and the Fermilab Tevatron, gamma p data from DESY HERA,
and gamma gamma data from CERN LEP2 allow us to test the universality of the
fragmentation functions predicted by the factorization theorem. Furthermore, we
perform comparisons with (e^+e^-)-annihilation data from LEP2 so as to test the
scaling violations predicted by the Altarelli-Parisi evolution equations.
|
[
{
"created": "Sun, 12 Nov 2000 12:18:21 GMT",
"version": "v1"
}
] |
2014-11-17
|
[
[
"Kniehl",
"B. A.",
""
],
[
"Kramer",
"G.",
""
],
[
"Poetter",
"B.",
""
]
] |
Using fragmentation functions for charged pions, charged kaons, and (anti)protons recently extracted from experimental data of e^+e^- annihilation at the Z-boson resonance and at centre-of-mass energy root(s) = 29 GeV, we perform a global study of inclusive charged-hadron production in p anti-p, gamma p, and gamma gamma collisions at next-to-leading order in the parton model of quantum chromodynamics. Comparisons of our results with p anti-p data from CERN S p anti-p S and the Fermilab Tevatron, gamma p data from DESY HERA, and gamma gamma data from CERN LEP2 allow us to test the universality of the fragmentation functions predicted by the factorization theorem. Furthermore, we perform comparisons with (e^+e^-)-annihilation data from LEP2 so as to test the scaling violations predicted by the Altarelli-Parisi evolution equations.
|
1811.06465
|
Lydia Beresford
|
Lydia Beresford, Jesse Liu
|
Photon collider search strategy for sleptons and dark matter at the LHC
|
4 pages + bibliography, 3 figures
|
Phys. Rev. Lett. 123, 141801 (2019)
|
10.1103/PhysRevLett.123.141801
| null |
hep-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We propose a search strategy using the LHC as a photon collider to open
sensitivity to scalar lepton (slepton $\tilde{\ell}$) production with masses
around 15 to 60 GeV above that of neutralino dark matter $\tilde{\chi}^0_1$.
This region is favored by relic abundance and muon $(g-2)_\mu$ arguments.
However, conventional searches are hindered by the irreducible diboson
background. We overcome this obstruction by measuring initial state kinematics
and the missing momentum four-vector in proton-tagged ultraperipheral
collisions using forward detectors. We demonstrate sensitivity beyond LEP for
slepton masses of up to 220 GeV for $ 15 \lesssim \Delta m(\tilde{\ell},
\tilde{\chi}^0_1) \lesssim 60$ GeV with 100 fb$^{-1}$ of 13 TeV proton
collisions. We encourage the LHC collaborations to open this forward frontier
for discovering new physics.
|
[
{
"created": "Thu, 15 Nov 2018 16:56:01 GMT",
"version": "v1"
}
] |
2019-10-09
|
[
[
"Beresford",
"Lydia",
""
],
[
"Liu",
"Jesse",
""
]
] |
We propose a search strategy using the LHC as a photon collider to open sensitivity to scalar lepton (slepton $\tilde{\ell}$) production with masses around 15 to 60 GeV above that of neutralino dark matter $\tilde{\chi}^0_1$. This region is favored by relic abundance and muon $(g-2)_\mu$ arguments. However, conventional searches are hindered by the irreducible diboson background. We overcome this obstruction by measuring initial state kinematics and the missing momentum four-vector in proton-tagged ultraperipheral collisions using forward detectors. We demonstrate sensitivity beyond LEP for slepton masses of up to 220 GeV for $ 15 \lesssim \Delta m(\tilde{\ell}, \tilde{\chi}^0_1) \lesssim 60$ GeV with 100 fb$^{-1}$ of 13 TeV proton collisions. We encourage the LHC collaborations to open this forward frontier for discovering new physics.
|
1910.13776
|
Walter Grimus
|
Walter Grimus
|
Revisiting the quantum field theory of neutrino oscillations in vacuum
|
26 pages, one figure, misprints corrected
| null |
10.1088/1361-6471/ab716f
|
UWThPh-2019-31
|
hep-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We consider neutrino oscillations in vacuum in the framework of quantum field
theory in which neutrino production and detection processes are part of a
single Feynman diagram and the corresponding cross section is computed in the
standard way, i.e. with final states represented by plane waves. We use
assumptions which are realized in actual experiments and concentrate on the
detection process. Moreover, we also allow for a finite time interval of length
$\tau$ during which the detector records neutrino events. In this context we
are motivated by accelerator-neutrino oscillation experiments where data taking
is synchronized in time with the proton spill time of the accelerator. Given
the final momenta and the direction of neutrino propagation, we find that in
the oscillation amplitude---for all practical purposes---the neutrino energy
$Q$ is fixed, apart from an interval of order $2\pi\hbar/\tau$ around a mean
energy $\bar Q$; this is an expression of energy non-conservation or the
time-energy uncertainty relation in the detection process due to $\tau <
\infty$. We derive in excellent approximation that in the amplitude the
oscillation effect originates from massive neutrinos with the same energy $\bar
Q$, i.e. oscillations take place in space without any decoherece effect, while
the remaining integration over $Q$ in the interval of order $2\pi\hbar/\tau$
around $\bar Q$ results in a time-correlation function expressing the time
delay between neutrino production and detection.
|
[
{
"created": "Wed, 30 Oct 2019 11:18:05 GMT",
"version": "v1"
},
{
"created": "Tue, 5 Nov 2019 17:06:45 GMT",
"version": "v2"
},
{
"created": "Fri, 24 Jan 2020 16:13:54 GMT",
"version": "v3"
},
{
"created": "Wed, 8 Apr 2020 08:05:45 GMT",
"version": "v4"
}
] |
2020-08-26
|
[
[
"Grimus",
"Walter",
""
]
] |
We consider neutrino oscillations in vacuum in the framework of quantum field theory in which neutrino production and detection processes are part of a single Feynman diagram and the corresponding cross section is computed in the standard way, i.e. with final states represented by plane waves. We use assumptions which are realized in actual experiments and concentrate on the detection process. Moreover, we also allow for a finite time interval of length $\tau$ during which the detector records neutrino events. In this context we are motivated by accelerator-neutrino oscillation experiments where data taking is synchronized in time with the proton spill time of the accelerator. Given the final momenta and the direction of neutrino propagation, we find that in the oscillation amplitude---for all practical purposes---the neutrino energy $Q$ is fixed, apart from an interval of order $2\pi\hbar/\tau$ around a mean energy $\bar Q$; this is an expression of energy non-conservation or the time-energy uncertainty relation in the detection process due to $\tau < \infty$. We derive in excellent approximation that in the amplitude the oscillation effect originates from massive neutrinos with the same energy $\bar Q$, i.e. oscillations take place in space without any decoherece effect, while the remaining integration over $Q$ in the interval of order $2\pi\hbar/\tau$ around $\bar Q$ results in a time-correlation function expressing the time delay between neutrino production and detection.
|
hep-ph/9412270
|
John Warren Mcintosh
|
Glennys R. Farrar and John W. McIntosh, Jr
|
Scattering from a Domain Wall in a Spontaneously Broken Gauge Theory
|
48 pages, 10 figures, LaTeX / epsf, revised to include references to
earlier related work
|
Phys.Rev. D51 (1995) 5889-5904
|
10.1103/PhysRevD.51.5889
|
RU-94-59
|
hep-ph
| null |
We study the interaction of particles with a domain wall at a
symmetry-breaking phase transition by perturbing about the domain wall
solution. We find the particulate excitations appropriate near the domain wall
and relate them to the particles present far from the wall in the uniform
broken and unbroken phases. For a quartic Higgs potential we find analytic
solutions to the equations of motion and derive reflection and transmission
coefficients. We discover several bound states for particles near the wall.
Finally, we apply our results to the electroweak phase transition in the
standard model.
|
[
{
"created": "Fri, 9 Dec 1994 20:07:43 GMT",
"version": "v1"
},
{
"created": "Tue, 20 Dec 1994 20:55:14 GMT",
"version": "v2"
}
] |
2012-08-27
|
[
[
"Farrar",
"Glennys R.",
""
],
[
"McIntosh,",
"John W.",
"Jr"
]
] |
We study the interaction of particles with a domain wall at a symmetry-breaking phase transition by perturbing about the domain wall solution. We find the particulate excitations appropriate near the domain wall and relate them to the particles present far from the wall in the uniform broken and unbroken phases. For a quartic Higgs potential we find analytic solutions to the equations of motion and derive reflection and transmission coefficients. We discover several bound states for particles near the wall. Finally, we apply our results to the electroweak phase transition in the standard model.
|
hep-ph/9608300
|
Leonid Burakovsky
|
L. Burakovsky and L.P. Horwitz
|
Gell-Mann--Okubo Mass Formula for an SU(4) Meson Hexadecuplet
|
11 pages, LaTeX
|
Found.Phys.Lett. 10 (1997) 131
|
10.1007/BF02764235
|
LA-UR-96-2415, IASSNS-HEP-96/81
|
hep-ph
| null |
Using a linear mass spectrum of an $SU(4)$ meson hexadecuplet, we derive the
Gell-Mann--Okubo mass formula for the charmed mesons, in good agreement with
experiment. Possible generalization of this method to a higher symmetry group
is briefly discussed.
|
[
{
"created": "Fri, 9 Aug 1996 17:59:06 GMT",
"version": "v1"
}
] |
2009-10-28
|
[
[
"Burakovsky",
"L.",
""
],
[
"Horwitz",
"L. P.",
""
]
] |
Using a linear mass spectrum of an $SU(4)$ meson hexadecuplet, we derive the Gell-Mann--Okubo mass formula for the charmed mesons, in good agreement with experiment. Possible generalization of this method to a higher symmetry group is briefly discussed.
|
2402.07541
|
Qi Zhou
|
Qi Zhou and Ben-Wei Zhang
|
$\mathcal{R}^2$ curvature-squared corrections on Langevin diffusion
coefficients
|
15 pages, 2 figures
| null | null | null |
hep-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The effect of finite coupling corrections to the Langevin diffusion
coefficients on a moving heavy quark in the Super Yang-Mills plasma is
investigated. These corrections are related to curvature squared corrections in
the corresponding gravity sector. We compare the results of both longitudinal
and perpendicular Langevin diffusion coefficients with those in $\mathcal{N}$=4
Super Yang-Mills plasma. It is observed that the curvature-squared corrections
influence the Langevin diffusion coefficients, and the corrections for both
Langevin diffusion coefficients demonstrate the dependence on the velocity of
the moving heavy quark and the specifics of the higher derivative correction.
In addition, we conduct calculations for the Langevin diffusion coefficients of
a moving heavy quark within the Gauss-Bonnet background.
|
[
{
"created": "Mon, 12 Feb 2024 10:09:45 GMT",
"version": "v1"
},
{
"created": "Wed, 20 Mar 2024 08:14:27 GMT",
"version": "v2"
}
] |
2024-03-21
|
[
[
"Zhou",
"Qi",
""
],
[
"Zhang",
"Ben-Wei",
""
]
] |
The effect of finite coupling corrections to the Langevin diffusion coefficients on a moving heavy quark in the Super Yang-Mills plasma is investigated. These corrections are related to curvature squared corrections in the corresponding gravity sector. We compare the results of both longitudinal and perpendicular Langevin diffusion coefficients with those in $\mathcal{N}$=4 Super Yang-Mills plasma. It is observed that the curvature-squared corrections influence the Langevin diffusion coefficients, and the corrections for both Langevin diffusion coefficients demonstrate the dependence on the velocity of the moving heavy quark and the specifics of the higher derivative correction. In addition, we conduct calculations for the Langevin diffusion coefficients of a moving heavy quark within the Gauss-Bonnet background.
|
gr-qc/0312085
|
David B. Malament
|
David B. Malament
|
On the Time Reversal Invariance of Classical Electromagnetic Theory
|
24 pages, 3 figure, forthcoming in Studies in History and Philosophy
of Modern Physics
|
Stud.Hist.Philos.Mod.Phys. 35 (2004) 295-315
| null | null |
gr-qc
| null |
David Albert claims that classical electromagnetic theory is not time
reversal invariant. He acknowledges that all physics books say that it is, but
claims they are "simply wrong" because they rely on an incorrect account of how
the time reversal operator acts on magnetic fields. On that account, electric
fields are left intact by the operator, but magnetic fields are inverted.
Albert sees no reason for the asymmetric treatment, and insists that neither
field should be inverted. I argue, to the contrary, that the inversion of
magnetic fields makes good sense and is, in fact, forced by elementary
geometric considerations. I also suggest a way of thinking about the time
reversal invariance of classical electromagnetic theory -- one that makes use
of the invariant four-dimensional formulation of the theory -- that makes no
reference to magnetic fields at all. It is my hope that it will be of interest
in its own right, Albert aside. It has the advantage that it allows for
arbitrary curvature in the background spacetime structure, and is therefore
suitable for the framework of general relativity. The only assumption one needs
is temporal orientability.
|
[
{
"created": "Thu, 18 Dec 2003 14:43:12 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Malament",
"David B.",
""
]
] |
David Albert claims that classical electromagnetic theory is not time reversal invariant. He acknowledges that all physics books say that it is, but claims they are "simply wrong" because they rely on an incorrect account of how the time reversal operator acts on magnetic fields. On that account, electric fields are left intact by the operator, but magnetic fields are inverted. Albert sees no reason for the asymmetric treatment, and insists that neither field should be inverted. I argue, to the contrary, that the inversion of magnetic fields makes good sense and is, in fact, forced by elementary geometric considerations. I also suggest a way of thinking about the time reversal invariance of classical electromagnetic theory -- one that makes use of the invariant four-dimensional formulation of the theory -- that makes no reference to magnetic fields at all. It is my hope that it will be of interest in its own right, Albert aside. It has the advantage that it allows for arbitrary curvature in the background spacetime structure, and is therefore suitable for the framework of general relativity. The only assumption one needs is temporal orientability.
|
1103.3085
|
Hrayr Matevosyan
|
Hrayr H. Matevosyan, Anthony W. Thomas and Wolfgang Bentz
|
Monte Carlo Simulations of Hadronic Fragmentation Functions using
NJL-Jet Model
|
27 pages, 13 figures
|
Phys.Rev.D83:114010,2011
|
10.1103/PhysRevD.83.114010
|
ADP-11-12/T734
|
hep-ph nucl-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The recently developed Nambu-Jona-Lasinio (NJL) - Jet model is used as an
effective chiral quark theory to calculate the quark fragmentation functions to
pions, kaons, nucleons, and antinucleons. The effects of the vector mesons rho,
K* and phi on the production of secondary pions and kaons are included. The
fragmentation processes to nucleons and antinucleons are described by using the
quark-diquark picture, which has been shown to give a reasonable description of
quark distribution functions. We incorporate effects of next-to-leading order
(NLO) in the Q^2 evolution, and compare our results with the empirical
fragmentation functions.
|
[
{
"created": "Wed, 16 Mar 2011 03:20:51 GMT",
"version": "v1"
},
{
"created": "Fri, 3 Jun 2011 01:15:07 GMT",
"version": "v2"
}
] |
2011-06-13
|
[
[
"Matevosyan",
"Hrayr H.",
""
],
[
"Thomas",
"Anthony W.",
""
],
[
"Bentz",
"Wolfgang",
""
]
] |
The recently developed Nambu-Jona-Lasinio (NJL) - Jet model is used as an effective chiral quark theory to calculate the quark fragmentation functions to pions, kaons, nucleons, and antinucleons. The effects of the vector mesons rho, K* and phi on the production of secondary pions and kaons are included. The fragmentation processes to nucleons and antinucleons are described by using the quark-diquark picture, which has been shown to give a reasonable description of quark distribution functions. We incorporate effects of next-to-leading order (NLO) in the Q^2 evolution, and compare our results with the empirical fragmentation functions.
|
1510.04575
|
Shinya Matsuzaki
|
Shinya Matsuzaki
|
One-Family Walking Technicolor in Light of LHC Run-II
|
latex, 15 pages, contribution to Sakata Memorial KMI Workshop on
"Origin of Mass and Strong Coupling Gauge Theories (SCGT15)", 3-6 March 2015,
Nagoya University; some comments and references added
| null | null | null |
hep-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The LHC Higgs can be identified as the technidilaton, a composite scalar,
arising as a pseudo Nambu-Goldstone boson for the spontaneous breaking of scale
symmetry in walking technicolor. One interesting candidate for the walking
technicolor is the QCD with the large number of fermion flavors, involving the
one-family model having the eight-fermion flavors. The smallness of the
technidilaton mass can be ensured by the generic walking feature, Miransky
scaling, and the presence of the "anti-Veneziano limit" characteristic to the
large-flavor walking scenario. To tell the standard-model Higgs from the
technidilaton, one needs to wait for the precise estimate of the Higgs
couplings to the standard model particles, which is expected at the ongoing
LHC-Run II. In this talk the technidilaton phenomenology in comparison with the
LHC Run-I data is summarized with the special emphasis placed on the presence
of the anti-Veneziano limit supporting the lightness of technidilaton. Besides
the technidilaton, the walking technicolor predicts the rich particle spectrum
such as technipions and technirho mesons, arising as composite particles formed
by technifermions. The LHC phenomenology of those technihadrons and the
discovery channels are also discussed, which are smoking-guns of the walking
technicolor, to be accessible at the LHC-Run II.
|
[
{
"created": "Thu, 15 Oct 2015 15:14:18 GMT",
"version": "v1"
},
{
"created": "Fri, 23 Oct 2015 10:12:12 GMT",
"version": "v2"
}
] |
2015-10-26
|
[
[
"Matsuzaki",
"Shinya",
""
]
] |
The LHC Higgs can be identified as the technidilaton, a composite scalar, arising as a pseudo Nambu-Goldstone boson for the spontaneous breaking of scale symmetry in walking technicolor. One interesting candidate for the walking technicolor is the QCD with the large number of fermion flavors, involving the one-family model having the eight-fermion flavors. The smallness of the technidilaton mass can be ensured by the generic walking feature, Miransky scaling, and the presence of the "anti-Veneziano limit" characteristic to the large-flavor walking scenario. To tell the standard-model Higgs from the technidilaton, one needs to wait for the precise estimate of the Higgs couplings to the standard model particles, which is expected at the ongoing LHC-Run II. In this talk the technidilaton phenomenology in comparison with the LHC Run-I data is summarized with the special emphasis placed on the presence of the anti-Veneziano limit supporting the lightness of technidilaton. Besides the technidilaton, the walking technicolor predicts the rich particle spectrum such as technipions and technirho mesons, arising as composite particles formed by technifermions. The LHC phenomenology of those technihadrons and the discovery channels are also discussed, which are smoking-guns of the walking technicolor, to be accessible at the LHC-Run II.
|
1206.7028
|
Erdogan Akyaz\'i
|
Erdogan Akyazi, Gokhan Unel, Metin Yilmaz
|
Comparison of Cut-Based and Matrix Element Method Results for Beyond
Standard Model Quarks
|
16 pages, 8 figures
| null |
10.5506/APhysPolB.44.1273
| null |
hep-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this work, two different methods for extracting the mass of a new quark
from the (pseudo) data are compared: the classical cut-based method and the
matrix element method. As a concrete example a fourth family up type quark is
searched in p-p collisions of 7 TeV center of mass energy. We have shown that
even with very small number of events, Matrix Element Method gives better
estimations for the mass value and its error, especially for event samples in
which Signal to Background ratio is greater than 0.2.
|
[
{
"created": "Fri, 29 Jun 2012 13:45:15 GMT",
"version": "v1"
},
{
"created": "Mon, 2 Jul 2012 01:46:36 GMT",
"version": "v2"
},
{
"created": "Mon, 30 Jul 2012 15:45:02 GMT",
"version": "v3"
},
{
"created": "Tue, 28 May 2013 23:27:10 GMT",
"version": "v4"
}
] |
2015-06-05
|
[
[
"Akyazi",
"Erdogan",
""
],
[
"Unel",
"Gokhan",
""
],
[
"Yilmaz",
"Metin",
""
]
] |
In this work, two different methods for extracting the mass of a new quark from the (pseudo) data are compared: the classical cut-based method and the matrix element method. As a concrete example a fourth family up type quark is searched in p-p collisions of 7 TeV center of mass energy. We have shown that even with very small number of events, Matrix Element Method gives better estimations for the mass value and its error, especially for event samples in which Signal to Background ratio is greater than 0.2.
|
hep-ph/9607204
|
Georges Grunberg
|
G.Grunberg
|
Nucleon spin structure,topological susceptibility and the $\eta^\prime$
singlet axial vector coupling
|
Latex 209,10 pages,no figures
|
Phys.Lett. B388 (1996) 173-178
|
10.1016/0370-2693(96)01132-X
| null |
hep-ph
| null |
The observed small value of the first moment of the polarized nucleon spin
structure function $g_1$ may be interpreted, in the Veneziano--Shore approach,
as a suppression of the first moment $\chi^\prime(0)$ of the QCD topological
susceptibility. I give an extension of the Witten--Veneziano argument for the
$U(1)$ problem, which yields the $O(1/N)$ correction to the $N = \infty$
relation $\chi^\prime(0)/F^2_0 = 1$ (where $F_0$ is the $\eta^\prime$ axial
vector coupling).The correction, although negative, seems too small to account
for the data. I further argue that the
$(\eta,\eta^\prime)\rightarrow\gamma\gamma$ and $J/\psi\rightarrow (\eta ,
\eta^\prime)\gamma$ decays indicate an enhancement rather than a suppression of
$F_0$. A substantial gluon-like contribution in $\langle 0\vert\partial^\mu
j^{(0)}_{\mu_5} \vert\gamma\gamma \rangle \vert_{q^2=0}$,which could parallel a
similar one in the corresponding nucleon matrix element,is suggested.
|
[
{
"created": "Mon, 1 Jul 1996 14:50:13 GMT",
"version": "v1"
}
] |
2009-10-28
|
[
[
"Grunberg",
"G.",
""
]
] |
The observed small value of the first moment of the polarized nucleon spin structure function $g_1$ may be interpreted, in the Veneziano--Shore approach, as a suppression of the first moment $\chi^\prime(0)$ of the QCD topological susceptibility. I give an extension of the Witten--Veneziano argument for the $U(1)$ problem, which yields the $O(1/N)$ correction to the $N = \infty$ relation $\chi^\prime(0)/F^2_0 = 1$ (where $F_0$ is the $\eta^\prime$ axial vector coupling).The correction, although negative, seems too small to account for the data. I further argue that the $(\eta,\eta^\prime)\rightarrow\gamma\gamma$ and $J/\psi\rightarrow (\eta , \eta^\prime)\gamma$ decays indicate an enhancement rather than a suppression of $F_0$. A substantial gluon-like contribution in $\langle 0\vert\partial^\mu j^{(0)}_{\mu_5} \vert\gamma\gamma \rangle \vert_{q^2=0}$,which could parallel a similar one in the corresponding nucleon matrix element,is suggested.
|
2008.13756
|
Vladimir Khatsymovsky
|
V.M. Khatsymovsky
|
On the discrete version of the Schwarzschild problem
|
24 pages, 1 figure; Special issue "Selected Papers from the 17th
Russian Gravitational Conference -- International Conference on Gravitation,
Cosmology and Astrophysics (RUSGRAV-17)"; explanations and refs added
|
Universe, Vol. 6, No.10, 185 (2020)
|
10.3390/universe6100185
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We consider a Schwarzschild type solution in the discrete Regge calculus
formulation of general relativity quantized within the path integral approach.
Earlier, we found a mechanism of a loose fixation of the background scale of
Regge lengths. This elementary length scale is defined by the Planck scale and
some free parameter of such a quantum extension of the theory. Besides, Regge
action was reduced to an expansion over metric variations between the
tetrahedra and, in the main approximation, is a finite-difference form of the
Hilbert-Einstein action. Using for the Schwarzschild problem a priori general
non-spherically symmetrical ansatz, we get finite-difference equations for its
discrete version. This defines a solution which at large distances is close to
the continuum Schwarzschild geometry, and the metric and effective curvature at
the center are cut off at the elementary length scale. Slow rotation can also
be taken into account (Lense-Thirring-like metric). Thus we get a general
approach to the classical background in the quantum framework in zero order: it
is an optimal starting point for the perturbative expansion of the theory;
finite-difference equations are classical, the elementary length scale has
quantum origin. Singularities, if any, are resolved.
|
[
{
"created": "Mon, 31 Aug 2020 17:23:25 GMT",
"version": "v1"
},
{
"created": "Wed, 21 Oct 2020 15:17:33 GMT",
"version": "v2"
}
] |
2020-10-22
|
[
[
"Khatsymovsky",
"V. M.",
""
]
] |
We consider a Schwarzschild type solution in the discrete Regge calculus formulation of general relativity quantized within the path integral approach. Earlier, we found a mechanism of a loose fixation of the background scale of Regge lengths. This elementary length scale is defined by the Planck scale and some free parameter of such a quantum extension of the theory. Besides, Regge action was reduced to an expansion over metric variations between the tetrahedra and, in the main approximation, is a finite-difference form of the Hilbert-Einstein action. Using for the Schwarzschild problem a priori general non-spherically symmetrical ansatz, we get finite-difference equations for its discrete version. This defines a solution which at large distances is close to the continuum Schwarzschild geometry, and the metric and effective curvature at the center are cut off at the elementary length scale. Slow rotation can also be taken into account (Lense-Thirring-like metric). Thus we get a general approach to the classical background in the quantum framework in zero order: it is an optimal starting point for the perturbative expansion of the theory; finite-difference equations are classical, the elementary length scale has quantum origin. Singularities, if any, are resolved.
|
2211.16526
|
Zhen Zhong
|
Zhen Zhong, Vitor Cardoso, Elisa Maggio
|
On the instability of ultracompact horizonless spacetimes
|
13 pages, 12 figures, substantial improvements and clarifications.
Results remain unchanged: this work shows that a class of compact object
models are linearly stable when light rings are present but ergoregions are
absent. Version to appear in Physical Review D
| null |
10.1103/PhysRevD.107.044035
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Motivated by recent results reporting the instability of horizonless objects
with stable light rings, we revisit the linearized stability of such
structures. In particular, we consider an exterior Kerr spacetime truncated at
a surface where Dirichlet conditions on a massless scalar are imposed.This
spacetime has ergoregions and light rings when the surface is placed
sufficiently deep in the gravitational potential. We establish that the
spacetime is linearly, mode-unstable when it is sufficiently compact, in a
mechanism associated with the ergoregion. In particular, such instability has
associated zero-modes. At large multipole number the critical surface location
for zero modes to exist is precisely the location of the ergosurface along the
equator. We show that such modes don't exist when the surface is outside the
ergoregion, and that any putative linear instability mechanism acts on
timescales $\tau \gtrsim 10^5 M$, where $M$ is the black hole mass. Our results
indicate therefore that at least certain classes of objects are linearly stable
in the absence of ergoregions, even if rotation and light rings are present.
|
[
{
"created": "Tue, 29 Nov 2022 19:00:03 GMT",
"version": "v1"
},
{
"created": "Sun, 4 Dec 2022 13:38:44 GMT",
"version": "v2"
},
{
"created": "Mon, 6 Feb 2023 15:56:38 GMT",
"version": "v3"
}
] |
2023-03-01
|
[
[
"Zhong",
"Zhen",
""
],
[
"Cardoso",
"Vitor",
""
],
[
"Maggio",
"Elisa",
""
]
] |
Motivated by recent results reporting the instability of horizonless objects with stable light rings, we revisit the linearized stability of such structures. In particular, we consider an exterior Kerr spacetime truncated at a surface where Dirichlet conditions on a massless scalar are imposed.This spacetime has ergoregions and light rings when the surface is placed sufficiently deep in the gravitational potential. We establish that the spacetime is linearly, mode-unstable when it is sufficiently compact, in a mechanism associated with the ergoregion. In particular, such instability has associated zero-modes. At large multipole number the critical surface location for zero modes to exist is precisely the location of the ergosurface along the equator. We show that such modes don't exist when the surface is outside the ergoregion, and that any putative linear instability mechanism acts on timescales $\tau \gtrsim 10^5 M$, where $M$ is the black hole mass. Our results indicate therefore that at least certain classes of objects are linearly stable in the absence of ergoregions, even if rotation and light rings are present.
|
hep-ph/0403263
|
Pedro Fernando Simoes Costa
|
Pedro Costa, M. C. Ruivo, Yu. L. Kalinovsky
|
Anomalous decay of pion and eta at finite temperature
|
4 pages, 4 figures, PRC version
|
Phys.Rev. C70 (2004) 048202
|
10.1103/PhysRevC.70.048202
| null |
hep-ph
| null |
We study the anomalous decays $\pi^0, \eta \to\gamma\gamma$ in the framework
of the three--flavor Nambu--Jona-Lasinio [NJL] model at finite temperature. The
similarities and differences between these results and those obtained at zero
temperature and finite density are discussed. In both cases the lifetimes of
these mesons decrease significantly at the critical point, although this might
not be sufficient to observe enhancement of these decays in heavy-ion
collisions.
|
[
{
"created": "Thu, 25 Mar 2004 15:17:21 GMT",
"version": "v1"
},
{
"created": "Mon, 11 Oct 2004 18:03:27 GMT",
"version": "v2"
}
] |
2007-05-23
|
[
[
"Costa",
"Pedro",
""
],
[
"Ruivo",
"M. C.",
""
],
[
"Kalinovsky",
"Yu. L.",
""
]
] |
We study the anomalous decays $\pi^0, \eta \to\gamma\gamma$ in the framework of the three--flavor Nambu--Jona-Lasinio [NJL] model at finite temperature. The similarities and differences between these results and those obtained at zero temperature and finite density are discussed. In both cases the lifetimes of these mesons decrease significantly at the critical point, although this might not be sufficient to observe enhancement of these decays in heavy-ion collisions.
|
1208.5255
|
Arkadiusz Trawinski
|
Stanis{\l}aw D. G{\l}azek, Arkadiusz P. Trawi\'nski
|
Neutrino oscillations in the front form of Hamiltonian dynamics
|
revtex4, 10 pages
|
Phys. Rev. D 87, 025002 (2013)
|
10.1103/PhysRevD.87.025002
| null |
hep-ph nucl-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Since future, precise theory of neutrino oscillations should include the
understanding of the neutrino mass generation and a precise, relativistic
description of hadrons, and observing that such a future theory may require
Dirac's FF of Hamiltonian dynamics, we provide a preliminary FF description of
neutrino oscillations using the Feynman--Gell-Mann-Levy version of an effective
theory in which leptons interact directly with whole nucleons and pions,
instead of with quarks via intermediate bosons. The interactions are treated in
the lowest-order perturbative expansion in the coupling constants in the
effective theory, including a perturbative solution of the coupled constraint
equations. Despite missing quarks and their binding mechanism, the effective
Hamiltonian description is sufficiently precise for showing that the standard
oscillation formula results from the interference of amplitudes with different
neutrinos in virtual intermediate states. This holds provided that the inherent
experimental uncertainties of preparing beams of incoming and measuring rates
of production of outgoing particles are large enough for all of the different
neutrino intermediate states to contribute as alternative virtual paths through
which the long-baseline scattering process can manifest itself. The result that
an approximate, effective FF theory reproduces the standard oscillation formula
at the level of transition rates for currently considered long-baseline
experiments--even though the space-time development of scattering is traced
differently and the relevant interaction Hamiltonians are constructed
differently than in the commonly used IF of dynamics--has two implications. It
shows that the common interpretation of experimental results is not the only
one, and it opens the possibility of considering more precise theories taking
advantage of the features of the FF that are not available in the IF.
|
[
{
"created": "Sun, 26 Aug 2012 21:30:14 GMT",
"version": "v1"
},
{
"created": "Sun, 6 Jan 2013 10:53:33 GMT",
"version": "v2"
}
] |
2013-01-09
|
[
[
"Głazek",
"Stanisław D.",
""
],
[
"Trawiński",
"Arkadiusz P.",
""
]
] |
Since future, precise theory of neutrino oscillations should include the understanding of the neutrino mass generation and a precise, relativistic description of hadrons, and observing that such a future theory may require Dirac's FF of Hamiltonian dynamics, we provide a preliminary FF description of neutrino oscillations using the Feynman--Gell-Mann-Levy version of an effective theory in which leptons interact directly with whole nucleons and pions, instead of with quarks via intermediate bosons. The interactions are treated in the lowest-order perturbative expansion in the coupling constants in the effective theory, including a perturbative solution of the coupled constraint equations. Despite missing quarks and their binding mechanism, the effective Hamiltonian description is sufficiently precise for showing that the standard oscillation formula results from the interference of amplitudes with different neutrinos in virtual intermediate states. This holds provided that the inherent experimental uncertainties of preparing beams of incoming and measuring rates of production of outgoing particles are large enough for all of the different neutrino intermediate states to contribute as alternative virtual paths through which the long-baseline scattering process can manifest itself. The result that an approximate, effective FF theory reproduces the standard oscillation formula at the level of transition rates for currently considered long-baseline experiments--even though the space-time development of scattering is traced differently and the relevant interaction Hamiltonians are constructed differently than in the commonly used IF of dynamics--has two implications. It shows that the common interpretation of experimental results is not the only one, and it opens the possibility of considering more precise theories taking advantage of the features of the FF that are not available in the IF.
|
hep-ph/9409316
|
Sean Fleming Northwestern Univ.
|
E. Braaten, K. Cheung, S. Fleming, T.C. Yuan
|
Perturbative QCD Fragmentation Functions as a Model for Heavy-Quark
Fragmentation
|
24 Pages (Figures can be obtained by request), FERMILAB-PUB-94-305-T,
NUHEP-TH-94-16, UCD-94-28
|
Phys.Rev.D51:4819-4829,1995
|
10.1103/PhysRevD.51.4819
| null |
hep-ph
| null |
The perturbative QCD fragmentation functions for a heavy quark to fragment
into heavy-light mesons are studied in the heavy-quark limit. The fragmentation
functions for S-wave pseudoscalar and vector mesons are calculated to
next-to-leading order in the heavy-quark mass expansion using the methods of
heavy-quark effective theory. The results agree with the $m_b\to \infty$ limit
of the perturbative QCD fragmentation functions for $\bar b$ into $B_c$ and
$B_c^*$. We discuss the application of the perturbative QCD fragmentation
functions as a model for the fragmentation of heavy quarks into heavy-light
mesons. Using this model, we predict the fraction $P_{V}$ of heavy-light mesons
that are produced in the vector meson state as functions of the longitudinal
momentum fraction $z$ and the transverse momentum relative to the jet axis. The
fraction $P_V$ is predicted to vary from about 1/2 at small $z$ to almost 3/4
near $z=1$.
|
[
{
"created": "Thu, 15 Sep 1994 02:35:36 GMT",
"version": "v1"
}
] |
2010-11-01
|
[
[
"Braaten",
"E.",
""
],
[
"Cheung",
"K.",
""
],
[
"Fleming",
"S.",
""
],
[
"Yuan",
"T. C.",
""
]
] |
The perturbative QCD fragmentation functions for a heavy quark to fragment into heavy-light mesons are studied in the heavy-quark limit. The fragmentation functions for S-wave pseudoscalar and vector mesons are calculated to next-to-leading order in the heavy-quark mass expansion using the methods of heavy-quark effective theory. The results agree with the $m_b\to \infty$ limit of the perturbative QCD fragmentation functions for $\bar b$ into $B_c$ and $B_c^*$. We discuss the application of the perturbative QCD fragmentation functions as a model for the fragmentation of heavy quarks into heavy-light mesons. Using this model, we predict the fraction $P_{V}$ of heavy-light mesons that are produced in the vector meson state as functions of the longitudinal momentum fraction $z$ and the transverse momentum relative to the jet axis. The fraction $P_V$ is predicted to vary from about 1/2 at small $z$ to almost 3/4 near $z=1$.
|
hep-ph/0608103
|
Ted Barnes
|
T.Barnes (1 and 2) ((1) Physics Division, Oak Ridge National
Laboratory, (2) Dept. of Physics and Astronomy, Univ. of Tennessee)
|
The XYZs of Charmonium at BES
|
5 pages, 1 eps figure. Invited contribution to the International
Workshop on Tau-Charm Physics Charm2006 (5-7 June 2006, Beijing, China)
|
Int.J.Mod.Phys. A21 (2006) 5583-5591
|
10.1142/S0217751X0603477X
| null |
hep-ph nucl-th
| null |
This contribution reviews some recent developments in charmonium
spectroscopy, and discusses related theoretical predictions. The spectrum of
states, strong decays of states above open charm threshold, electromagnetic
transitions, and issues related to the recent discoveries of the "XYZ" states
are discussed. Contributions that BES can make to our understanding of
charmonium and related states are stressed in particular.
|
[
{
"created": "Wed, 9 Aug 2006 20:09:32 GMT",
"version": "v1"
}
] |
2009-11-11
|
[
[
"Barnes",
"T.",
"",
"1 and 2"
]
] |
This contribution reviews some recent developments in charmonium spectroscopy, and discusses related theoretical predictions. The spectrum of states, strong decays of states above open charm threshold, electromagnetic transitions, and issues related to the recent discoveries of the "XYZ" states are discussed. Contributions that BES can make to our understanding of charmonium and related states are stressed in particular.
|
1212.1386
|
Alexey Toporensky
|
S. Pavluchenko and A. Toporensky
|
Note on properties of exact cosmological solutions in Lovelock gravity
|
7 pages, no figures; small changes
|
Gravitation & Cosmology 20, 127 (2014)
|
10.1134/S0202289314020091
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We study some properties of exact cosmological solutions for a flat
multidimensional anisotropic Universe in Lovelock gravity. A particular
attention is paid to some features of solution in a general Lovelock gravity
which have no their counterparts in analogous solution of General Relativity.
We consider exponential solutions and so called generalized Milne solution and
discuss reasons for these solution to exist in Lovelock gravity and do not
exist in General Relativity.
|
[
{
"created": "Thu, 6 Dec 2012 17:23:51 GMT",
"version": "v1"
},
{
"created": "Thu, 12 Dec 2013 23:49:33 GMT",
"version": "v2"
}
] |
2014-06-11
|
[
[
"Pavluchenko",
"S.",
""
],
[
"Toporensky",
"A.",
""
]
] |
We study some properties of exact cosmological solutions for a flat multidimensional anisotropic Universe in Lovelock gravity. A particular attention is paid to some features of solution in a general Lovelock gravity which have no their counterparts in analogous solution of General Relativity. We consider exponential solutions and so called generalized Milne solution and discuss reasons for these solution to exist in Lovelock gravity and do not exist in General Relativity.
|
1501.03156
|
Nobuo Sato
|
Andrew Askew, Prerit Jaiswal, Takemichi Okui, Harrison B. Prosper,
Nobuo Sato
|
Prospect for measuring the CP phase in the $h\tau\tau$ coupling at the
LHC
|
Minor wording changes. The version published in PRD
|
Phys. Rev. D 91, 075014 (2015)
|
10.1103/PhysRevD.91.075014
|
JLAB-THY-15-2000
|
hep-ph hep-ex
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The search for a new source of CP violation is one of the most important
endeavors in particle physics. A particularly interesting way to perform this
search is to probe the CP phase in the $h\tau\tau$ coupling, as the phase is
currently completely unconstrained by all existing data. Recently, a novel
variable $\Theta$ was proposed for measuring the CP phase in the $h\tau\tau$
coupling through the $\tau^\pm \to \pi^\pm \pi^0 \nu$ decay mode. We examine
two crucial questions that the real LHC detectors must face, namely, the issue
of neutrino reconstruction and the effects of finite detector resolution. For
the former, we find strong evidence that the collinear approximation is the
best for the $\Theta$ variable. For the latter, we find that the angular
resolution is actually not an issue even though the reconstruction of $\Theta$
requires resolving the highly collimated $\pi^\pm$'s and $\pi^0$'s from the
$\tau$ decays. Instead, we find that it is the missing transverse energy
resolution that significantly limits the LHC reach for measuring the CP phase
via $\Theta$. With the current missing energy resolution, we find that with
$\sim 1000\,\textrm{fb}^{-1}$ the CP phase hypotheses $\Delta = 0^\circ$ (the
standard model value) and $\Delta = 90^\circ$ can be distinguished, at most, at
the 95\% confidence level.
|
[
{
"created": "Tue, 13 Jan 2015 21:00:10 GMT",
"version": "v1"
},
{
"created": "Thu, 15 Jan 2015 03:40:21 GMT",
"version": "v2"
},
{
"created": "Mon, 4 May 2015 13:27:40 GMT",
"version": "v3"
}
] |
2015-05-05
|
[
[
"Askew",
"Andrew",
""
],
[
"Jaiswal",
"Prerit",
""
],
[
"Okui",
"Takemichi",
""
],
[
"Prosper",
"Harrison B.",
""
],
[
"Sato",
"Nobuo",
""
]
] |
The search for a new source of CP violation is one of the most important endeavors in particle physics. A particularly interesting way to perform this search is to probe the CP phase in the $h\tau\tau$ coupling, as the phase is currently completely unconstrained by all existing data. Recently, a novel variable $\Theta$ was proposed for measuring the CP phase in the $h\tau\tau$ coupling through the $\tau^\pm \to \pi^\pm \pi^0 \nu$ decay mode. We examine two crucial questions that the real LHC detectors must face, namely, the issue of neutrino reconstruction and the effects of finite detector resolution. For the former, we find strong evidence that the collinear approximation is the best for the $\Theta$ variable. For the latter, we find that the angular resolution is actually not an issue even though the reconstruction of $\Theta$ requires resolving the highly collimated $\pi^\pm$'s and $\pi^0$'s from the $\tau$ decays. Instead, we find that it is the missing transverse energy resolution that significantly limits the LHC reach for measuring the CP phase via $\Theta$. With the current missing energy resolution, we find that with $\sim 1000\,\textrm{fb}^{-1}$ the CP phase hypotheses $\Delta = 0^\circ$ (the standard model value) and $\Delta = 90^\circ$ can be distinguished, at most, at the 95\% confidence level.
|
1211.1186
|
Ilya Gorbunov N
|
Gennady Kozlov
|
Dilaton vs Higgs: Nearly Conformal theory with confinement-like pattern
|
8 pages, 1 fig., Talk at the Conference "Quark Confinement and the
Hadron Spectrum X" (8-12 October, 2012, TUM Campus Garching, Munich, Germany)
to appear in the Proceedings
| null | null | null |
hep-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We consider the model containing a dilaton vs Higgs boson in the nearly
conformal sector (NCS). The potential of a dilaton in NCS is linearly rising
with distances. The light scalar dilaton would be one of the best candidates to
explain the LHC data in recent discovery of a Higgs-like resonance at 125 GeV.
|
[
{
"created": "Tue, 6 Nov 2012 11:31:32 GMT",
"version": "v1"
}
] |
2012-11-07
|
[
[
"Kozlov",
"Gennady",
""
]
] |
We consider the model containing a dilaton vs Higgs boson in the nearly conformal sector (NCS). The potential of a dilaton in NCS is linearly rising with distances. The light scalar dilaton would be one of the best candidates to explain the LHC data in recent discovery of a Higgs-like resonance at 125 GeV.
|
2007.02558
|
Hai-Yang Cheng
|
Hai-Yang Cheng, Chun-Khiang Chua
|
Branching Fractions and CP Violation in $B^-\to K^+K^-\pi^-$ and $B^-\to
\pi^+\pi^-\pi^-$ Decays
|
40 pages and 5 figures, discussions added on p.5 and p.9, version to
appear in PRD
|
Phys. Rev. D 102, 053006 (2020)
|
10.1103/PhysRevD.102.053006
| null |
hep-ph hep-ex
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We present in this work a study of tree-dominated charmless three-body decays
of $B$ mesons, $B^-\to K^+K^-\pi^-$ and $B^-\to\pi^+\pi^-\pi^-$, within the
factorization approach. The main results are: (i) There are two distinct
sources of nonresonant contributions: one arises from the $b\to u$ tree
transition and the other from the nonresonant matrix element of scalar
densities $\langle M_1M_2|\bar q_1 q_2|0\rangle^{\rm NR}$. It turns out that
even for tree-dominated three-body decays, dominant nonresonant contributions
originate from the penguin diagram rather than from the $b\to u$ tree process,
as implied by the large nonresonant component observed recently in the $\pi^-
K^+$ system which accounts for one third of the $B^-\to K^+K^-\pi^-$ rate. (ii)
The calculated branching fraction of $B^-\to f_2(1270)\pi^-\to K^+K^-\pi^-$ is
smaller than the LHCb by a factor of $\sim 7$ in its central value, but the
predicted $\B(B^-\to f_2(1270)\pi^-\to\pi^+\pi^-\pi^-)$ is consistent with the
data. Branching fractions of $B^-\to f_2(1270)\pi^-$ extracted from the LHCb
measurements of these two processes also differ by a factor of seven!
Therefore, it is likely that the $f_2(1270)$ contribution to $B^-\to
K^+K^-\pi^-$ is largely overestimated experimentally. Including $1/m_b$ power
corrections from penguin annihilation inferred from QCD factorization (QCDF), a
sizable CP asymmetry of 32\% in the $f_2(1270)$ component agrees with
experiment. (iii) A fraction of 5\% for the $\rho(1450)$ component in
$B^-\to\pi^+\pi^-\pi^-$ is in accordance with the theoretical expectation.
However, a large fraction of 30\% in $B^-\to K^+K^-\pi^-$ is entirely
unexpected. This issue needs to be clarified in the future.
|
[
{
"created": "Mon, 6 Jul 2020 07:13:34 GMT",
"version": "v1"
},
{
"created": "Tue, 7 Jul 2020 09:07:22 GMT",
"version": "v2"
},
{
"created": "Sat, 22 Aug 2020 03:00:05 GMT",
"version": "v3"
}
] |
2020-09-23
|
[
[
"Cheng",
"Hai-Yang",
""
],
[
"Chua",
"Chun-Khiang",
""
]
] |
We present in this work a study of tree-dominated charmless three-body decays of $B$ mesons, $B^-\to K^+K^-\pi^-$ and $B^-\to\pi^+\pi^-\pi^-$, within the factorization approach. The main results are: (i) There are two distinct sources of nonresonant contributions: one arises from the $b\to u$ tree transition and the other from the nonresonant matrix element of scalar densities $\langle M_1M_2|\bar q_1 q_2|0\rangle^{\rm NR}$. It turns out that even for tree-dominated three-body decays, dominant nonresonant contributions originate from the penguin diagram rather than from the $b\to u$ tree process, as implied by the large nonresonant component observed recently in the $\pi^- K^+$ system which accounts for one third of the $B^-\to K^+K^-\pi^-$ rate. (ii) The calculated branching fraction of $B^-\to f_2(1270)\pi^-\to K^+K^-\pi^-$ is smaller than the LHCb by a factor of $\sim 7$ in its central value, but the predicted $\B(B^-\to f_2(1270)\pi^-\to\pi^+\pi^-\pi^-)$ is consistent with the data. Branching fractions of $B^-\to f_2(1270)\pi^-$ extracted from the LHCb measurements of these two processes also differ by a factor of seven! Therefore, it is likely that the $f_2(1270)$ contribution to $B^-\to K^+K^-\pi^-$ is largely overestimated experimentally. Including $1/m_b$ power corrections from penguin annihilation inferred from QCD factorization (QCDF), a sizable CP asymmetry of 32\% in the $f_2(1270)$ component agrees with experiment. (iii) A fraction of 5\% for the $\rho(1450)$ component in $B^-\to\pi^+\pi^-\pi^-$ is in accordance with the theoretical expectation. However, a large fraction of 30\% in $B^-\to K^+K^-\pi^-$ is entirely unexpected. This issue needs to be clarified in the future.
|
1106.1649
|
Karim Benakli
|
Karim Benakli
|
Dirac Gauginos: A User Manual
|
4 pages, no figure. References added
| null |
10.1002/prop.201100071
| null |
hep-ph hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The issue of a Majorana, Dirac or pseudo-Dirac mass for gauginos must not be
reduced to a question of an extension of the Minimal Supersymmetric Standard
Model by extra states, parameters and phenomenological implications. On the
contrary, it is intimately related to the fundamental issue of the realization
of new symmetries in nature, R-symmetries. We present here a very dense
compilation of the main features of models with (pseudo-)Dirac gauginos.
|
[
{
"created": "Wed, 8 Jun 2011 20:00:23 GMT",
"version": "v1"
},
{
"created": "Mon, 20 Jun 2011 21:49:01 GMT",
"version": "v2"
}
] |
2015-05-28
|
[
[
"Benakli",
"Karim",
""
]
] |
The issue of a Majorana, Dirac or pseudo-Dirac mass for gauginos must not be reduced to a question of an extension of the Minimal Supersymmetric Standard Model by extra states, parameters and phenomenological implications. On the contrary, it is intimately related to the fundamental issue of the realization of new symmetries in nature, R-symmetries. We present here a very dense compilation of the main features of models with (pseudo-)Dirac gauginos.
|
hep-ph/9910221
|
Ahmed Ali
|
A. Ali (DESY, Hamburg), Patricia Ball (CERN), L.T. Handoko (DESY,
Hamburg), G. Hiller (SLAC)
|
A Comparative Study of the Decays $B \to (K,K^*) \ell^+ \ell^-$ in
Standard Model and Supersymmetric Theories
|
36 pages, 12 figures (require epsfig.sty), 8 Tables, LaTeX2e;
subsection 6.4 corrected, minor changes in numerical results, Figures 3 and 9
to 12 modified; submitted to Physical Review D
|
Phys.Rev.D61:074024,2000
|
10.1103/PhysRevD.61.074024
|
DESY 99-146, CERN-TH/99-298, LNF-99/026 (P), SLAC-PUB-8269 (October
1999)
|
hep-ph hep-ex
| null |
Using improved theoretical calculations of the decay form factors in the
Light Cone-QCD sum rule approach, we investigate the decay rates, dilepton
invariant mass spectra and the forward-backward (FB) asymmetry in the decays $B
\to (K,K^*) \ell^+ \ell^-$ ($\ell^\pm =e^\pm,\mu^\pm,\tau^\pm$) in the standard
model (SM) and a number of popular variants of the supersymmetric (SUSY)
models. Theoretical precision on the differential decay rates and FB-asymmetry
is estimated in these theories taking into account various parametric
uncertainties. We show that existing data on $B \to X_s \gamma$ and the
experimental upper limit on the branching ratio ${\cal B}(B \to K^* \mu^+
\mu^-)$ provide interesting bounds on the coefficients of the underlying
effective theory. We argue that the FB-asymmetry in $B \to K^* \ell^+ \ell^-$
constitutes a precision test of the SM and its measurement in forthcoming
experiments may reveal new physics. In particular, the presently allowed
large-$\tan \beta$ solutions in SUGRA models, as well as more general
flavor-violating SUSY models, yield FB-asymmetries which are characteristically
different from the corresponding ones in the SM.
|
[
{
"created": "Mon, 4 Oct 1999 17:30:52 GMT",
"version": "v1"
},
{
"created": "Fri, 22 Oct 1999 10:11:23 GMT",
"version": "v2"
}
] |
2011-03-23
|
[
[
"Ali",
"A.",
"",
"DESY, Hamburg"
],
[
"Ball",
"Patricia",
"",
"CERN"
],
[
"Handoko",
"L. T.",
"",
"DESY,\n Hamburg"
],
[
"Hiller",
"G.",
"",
"SLAC"
]
] |
Using improved theoretical calculations of the decay form factors in the Light Cone-QCD sum rule approach, we investigate the decay rates, dilepton invariant mass spectra and the forward-backward (FB) asymmetry in the decays $B \to (K,K^*) \ell^+ \ell^-$ ($\ell^\pm =e^\pm,\mu^\pm,\tau^\pm$) in the standard model (SM) and a number of popular variants of the supersymmetric (SUSY) models. Theoretical precision on the differential decay rates and FB-asymmetry is estimated in these theories taking into account various parametric uncertainties. We show that existing data on $B \to X_s \gamma$ and the experimental upper limit on the branching ratio ${\cal B}(B \to K^* \mu^+ \mu^-)$ provide interesting bounds on the coefficients of the underlying effective theory. We argue that the FB-asymmetry in $B \to K^* \ell^+ \ell^-$ constitutes a precision test of the SM and its measurement in forthcoming experiments may reveal new physics. In particular, the presently allowed large-$\tan \beta$ solutions in SUGRA models, as well as more general flavor-violating SUSY models, yield FB-asymmetries which are characteristically different from the corresponding ones in the SM.
|
hep-ph/9606393
|
Bernd Krause
|
Andrzej Czarnecki and Bernd Krause
|
Electroweak corrections to the muon anomalous magnetic moment
|
Latex, uses espcrc2. Talk presented at the 1996 Zeuthen Workshop on
Elementary Particle Theory, "QCD and QED in Higher Order", Rheinsberg,
Germany, April 21-26, 1996. The complete paper, including figures, is also
available via anonymous ftp at ftp://www-ttp.physik.uni-karlsruhe.de/ , or
via www at http://www-ttp.physik.uni-karlsruhe.de/cgi-bin/preprints/
|
Nucl.Phys.Proc.Suppl. 51C (1996) 148-153
| null |
TTP96-21
|
hep-ph
| null |
The two-loop electroweak radiative corrections to the muon's anomalous
magnetic moment, $a_\mu\equiv (g_\mu-2)/2$, are presented. We obtain an overall
22.6\% reduction in the electroweak contribution $a_\mu^{\rm EW}$ from
$195\times 10^{-11}$ to $151(4)\times 10^{-11}$. Implications for the full
standard model prediction and an upcoming high precision measurement of $a_\mu$
are briefly discussed. Some aspects of the calculations are discussed in
detail.
|
[
{
"created": "Thu, 20 Jun 1996 15:54:05 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Czarnecki",
"Andrzej",
""
],
[
"Krause",
"Bernd",
""
]
] |
The two-loop electroweak radiative corrections to the muon's anomalous magnetic moment, $a_\mu\equiv (g_\mu-2)/2$, are presented. We obtain an overall 22.6\% reduction in the electroweak contribution $a_\mu^{\rm EW}$ from $195\times 10^{-11}$ to $151(4)\times 10^{-11}$. Implications for the full standard model prediction and an upcoming high precision measurement of $a_\mu$ are briefly discussed. Some aspects of the calculations are discussed in detail.
|
2206.00083
|
Shahram Jalalzadeh
|
S. Jalalzadeh, S. M. M. Rasouli and P. V. Moniz
|
Shape Invariant Potentials in Supersymmetric Quantum Cosmology
|
19 pages, 3 figures, Review article, contribution to the special
issue on "Quantum Cosmology" in Universe
|
Universe, 8, 316 (2022)
|
10.3390/universe8060316
| null |
gr-qc hep-th quant-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this brief review, we comment on the concept of shape invariant
potentials, which is an essential feature in many settings of $N=2$
supersymmetric quantum mechanics. To motivate its application within
supersymmetric quantum cosmology, we present a case study to illustrate the
value of this promising tool. Concretely, we take a spatially flat FRW model in
the presence of a single scalar field, minimally coupled to gravity. Then, we
extract the associated Schr\"odinger-Wheeler-DeWitt equation, allowing for a
particular scope of factor ordering. Subsequently, we compute the corresponding
supersymmetric partner Hamiltonians, $H_1$ and $H_2$. Moreover, we point out
how the shape invariance property can be employed to bring a relation among
several factor orderings choices for our Schr\"odinger-Wheeler-DeWitt equation.
The ground state is retrieved, and the excited states easily written. Finally,
the Hamiltonians, $H_1$ and $H_2$ are explicitly presented within a $N=2$
supersymmetric quantum mechanics framework.
|
[
{
"created": "Tue, 31 May 2022 19:51:21 GMT",
"version": "v1"
}
] |
2022-06-07
|
[
[
"Jalalzadeh",
"S.",
""
],
[
"Rasouli",
"S. M. M.",
""
],
[
"Moniz",
"P. V.",
""
]
] |
In this brief review, we comment on the concept of shape invariant potentials, which is an essential feature in many settings of $N=2$ supersymmetric quantum mechanics. To motivate its application within supersymmetric quantum cosmology, we present a case study to illustrate the value of this promising tool. Concretely, we take a spatially flat FRW model in the presence of a single scalar field, minimally coupled to gravity. Then, we extract the associated Schr\"odinger-Wheeler-DeWitt equation, allowing for a particular scope of factor ordering. Subsequently, we compute the corresponding supersymmetric partner Hamiltonians, $H_1$ and $H_2$. Moreover, we point out how the shape invariance property can be employed to bring a relation among several factor orderings choices for our Schr\"odinger-Wheeler-DeWitt equation. The ground state is retrieved, and the excited states easily written. Finally, the Hamiltonians, $H_1$ and $H_2$ are explicitly presented within a $N=2$ supersymmetric quantum mechanics framework.
|
2407.08117
|
Mustafa Saeed
|
Mustafa Saeed and Viqar Husain
|
Quantum cosmology as a lattice in a box
|
6 pages
| null | null | null |
gr-qc
|
http://creativecommons.org/licenses/by/4.0/
|
We describe quantization schemes for scalar field cosmology in the metric
variables with fundamental discreteness imposed with a lattice. The variables
chosen for quantization determine the lattice, and each lattice produces
distinct effective equations derived from semiclassical states. We show that
requiring a bounce at the Planck density uniquely selects the volume lattice
and gives the same effective Friedmann equation as that obtained in loop
quantum cosmology. We also present conditions for the validity of the effective
equations.
|
[
{
"created": "Thu, 11 Jul 2024 01:22:21 GMT",
"version": "v1"
},
{
"created": "Mon, 29 Jul 2024 07:28:40 GMT",
"version": "v2"
}
] |
2024-07-30
|
[
[
"Saeed",
"Mustafa",
""
],
[
"Husain",
"Viqar",
""
]
] |
We describe quantization schemes for scalar field cosmology in the metric variables with fundamental discreteness imposed with a lattice. The variables chosen for quantization determine the lattice, and each lattice produces distinct effective equations derived from semiclassical states. We show that requiring a bounce at the Planck density uniquely selects the volume lattice and gives the same effective Friedmann equation as that obtained in loop quantum cosmology. We also present conditions for the validity of the effective equations.
|
2307.15533
|
Mehran Kamarpour
|
Mehran Kamarpour
|
Influence of tachyonic instability on the Schwinger effect in Higgs
inflation model
|
13 pages,10 figures. arXiv admin note: substantial text overlap with
arXiv:2307.00945
| null | null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We investigate the influence of the tachyonic instability on the Schwinger
effect in Higgs inflation model.In this work we identify the standard horizon
scale $ k_{H}=aH $ and the tachyonic instability $ k_{H}=aH|\zeta| ,
\zeta=\frac{{I}^{\prime}\left(\phi\right)\dot{\phi}}{H} $.This is the horizon
scale in which the given Fourier begins to become tachyonically
unstable.Influence of this scale appears by vanishing electromagnetic field
energy density and energy density of created charged particles due to the
Schwinger effect at the very beginning of inflation but does not alter
conclusions of our previous work in
Refs.\cite{Kamarpour:2022,Kamarpour:2023-I}.We use two coupling functions to
break conformal invariance of maxwell action.The simplest coupling function $
I\left(\phi\right)=\chi_{1}\frac{\phi}{M_{p}} $ and a curvature based coupling
function $ I\left(\phi\right)=
12\chi_{1}e^{\left(\sqrt{\frac{2}{3}}\frac{\phi}{M_{p}}\right)}\left[\frac{1}{3M_{p}^{2}}\left(4V\left(\phi\right)\right)+\frac{\sqrt{2}}{\sqrt{3}M_{p}}\left(\frac{dV}{d\phi}\right)\right]
$ where $V\left(\phi\right) $ is the potential of Higgs inflation in
Refs.\cite{Kamarpour:2022,Kamarpour:2023-I}.In fact, we find that only at the
very beginning of inflation both energy densities of electromagnetic field and
created charged particles vanish due to effect of tachyoinc instability.
|
[
{
"created": "Fri, 28 Jul 2023 12:52:26 GMT",
"version": "v1"
}
] |
2023-07-31
|
[
[
"Kamarpour",
"Mehran",
""
]
] |
We investigate the influence of the tachyonic instability on the Schwinger effect in Higgs inflation model.In this work we identify the standard horizon scale $ k_{H}=aH $ and the tachyonic instability $ k_{H}=aH|\zeta| , \zeta=\frac{{I}^{\prime}\left(\phi\right)\dot{\phi}}{H} $.This is the horizon scale in which the given Fourier begins to become tachyonically unstable.Influence of this scale appears by vanishing electromagnetic field energy density and energy density of created charged particles due to the Schwinger effect at the very beginning of inflation but does not alter conclusions of our previous work in Refs.\cite{Kamarpour:2022,Kamarpour:2023-I}.We use two coupling functions to break conformal invariance of maxwell action.The simplest coupling function $ I\left(\phi\right)=\chi_{1}\frac{\phi}{M_{p}} $ and a curvature based coupling function $ I\left(\phi\right)= 12\chi_{1}e^{\left(\sqrt{\frac{2}{3}}\frac{\phi}{M_{p}}\right)}\left[\frac{1}{3M_{p}^{2}}\left(4V\left(\phi\right)\right)+\frac{\sqrt{2}}{\sqrt{3}M_{p}}\left(\frac{dV}{d\phi}\right)\right] $ where $V\left(\phi\right) $ is the potential of Higgs inflation in Refs.\cite{Kamarpour:2022,Kamarpour:2023-I}.In fact, we find that only at the very beginning of inflation both energy densities of electromagnetic field and created charged particles vanish due to effect of tachyoinc instability.
|
1612.07507
|
Philippe Grandclement
|
Philippe Grandcl\'ement (LUTH)
|
Light rings and light points of boson stars
| null |
Phys. Rev. D 95, 084011 (2017)
|
10.1103/PhysRevD.95.084011
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
This work is devoted to the study of photon trajectories around rotating
boson stars. The basic properties of boson star models are given with a
particular emphasis on the high compactness those objects can have. Using an
effective potential method, circular orbits of photons around rotating boson
stars are then obtained, at least for relativistic enough configurations. A
particular class of light rings, in which the photons are at rest on a stable
orbit, is exhibited. By this one means that the associated worldline is
collinear to the Killing vector corresponding to the asymptotic time
translation symmetry. It is proposed to call those orbits light points. Their
existence is very specific to boson stars and the link between light points and
ergoregions is investigated.
|
[
{
"created": "Thu, 22 Dec 2016 09:49:51 GMT",
"version": "v1"
},
{
"created": "Tue, 4 Apr 2017 14:39:51 GMT",
"version": "v2"
}
] |
2017-04-12
|
[
[
"Grandclément",
"Philippe",
"",
"LUTH"
]
] |
This work is devoted to the study of photon trajectories around rotating boson stars. The basic properties of boson star models are given with a particular emphasis on the high compactness those objects can have. Using an effective potential method, circular orbits of photons around rotating boson stars are then obtained, at least for relativistic enough configurations. A particular class of light rings, in which the photons are at rest on a stable orbit, is exhibited. By this one means that the associated worldline is collinear to the Killing vector corresponding to the asymptotic time translation symmetry. It is proposed to call those orbits light points. Their existence is very specific to boson stars and the link between light points and ergoregions is investigated.
|
2001.01276
|
Anna Stasto
|
Michal Deak, Leonid Frankfurt, Mark Strikman and Anna Stasto
|
Taming of preasymptotic small x evolution within resummation framework
|
27 pages, 17 figures
| null |
10.1140/epjc/s10052-020-7861-6
| null |
hep-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
It is well understood that the leading logarithmic approximation for the
amplitudes of high energy processes is insufficient and that the
next-to-leading logarithmic effects are very large and lead to instability of
the solution. The resummation at low $x$, which includes kinematical
constraints and other corrections leads to stable result. Using previously
established resummation procedure we study in detail the preasymptotic effects
which occur in the solution to the resummed BFKL equation when the energy is
not very large. We find that in addition to the well known reduction of the
intercept, which governs the energy dependence of the gluon Green's function,
resummation leads to the delay of the onset of its small $x$ growth. Moreover
the gluon Green's function develops a dip or a plateau in wide range of
rapidities, which increases for large scales. The preasymptotic region in the
gluon Green's function extends to about $8$ units in rapidity for the
transverse scales of the order of $30-100 \; {\rm GeV} $. To visualize the
expected behavior of physical processes with two equal hard scales we calculate
the cross section of the process $\gamma^{*}+\gamma^{*}\to X$ to be probed at
future very high-energy electron-positron colliders. We find that at
$\gamma^*\gamma^*$ energies below $100 \; \rm GeV$ the BFKL Pomeron leads to
smaller value of the cross section than the Born approximation, and only starts
to dominate at energies about $100 \; \rm GeV$. This pattern is significantly
different from the one which we find using LL approximation. We also analyze
the transverse momentum contributions to the cross section for different
virtualities of the photons and find that the dominant contributions to the
integral over the transverse momenta comes from lower values than the the
external scales in the process under consideration.
|
[
{
"created": "Sun, 5 Jan 2020 17:31:48 GMT",
"version": "v1"
}
] |
2020-04-22
|
[
[
"Deak",
"Michal",
""
],
[
"Frankfurt",
"Leonid",
""
],
[
"Strikman",
"Mark",
""
],
[
"Stasto",
"Anna",
""
]
] |
It is well understood that the leading logarithmic approximation for the amplitudes of high energy processes is insufficient and that the next-to-leading logarithmic effects are very large and lead to instability of the solution. The resummation at low $x$, which includes kinematical constraints and other corrections leads to stable result. Using previously established resummation procedure we study in detail the preasymptotic effects which occur in the solution to the resummed BFKL equation when the energy is not very large. We find that in addition to the well known reduction of the intercept, which governs the energy dependence of the gluon Green's function, resummation leads to the delay of the onset of its small $x$ growth. Moreover the gluon Green's function develops a dip or a plateau in wide range of rapidities, which increases for large scales. The preasymptotic region in the gluon Green's function extends to about $8$ units in rapidity for the transverse scales of the order of $30-100 \; {\rm GeV} $. To visualize the expected behavior of physical processes with two equal hard scales we calculate the cross section of the process $\gamma^{*}+\gamma^{*}\to X$ to be probed at future very high-energy electron-positron colliders. We find that at $\gamma^*\gamma^*$ energies below $100 \; \rm GeV$ the BFKL Pomeron leads to smaller value of the cross section than the Born approximation, and only starts to dominate at energies about $100 \; \rm GeV$. This pattern is significantly different from the one which we find using LL approximation. We also analyze the transverse momentum contributions to the cross section for different virtualities of the photons and find that the dominant contributions to the integral over the transverse momenta comes from lower values than the the external scales in the process under consideration.
|
1102.1810
|
Hirotaka Yoshino
|
Hirotaka Yoshino
|
Black hole initial data in Gauss-Bonnet gravity: Momentarily static case
|
30 pages, 10 figures, submitted to PRD
|
Phys.Rev.D83:104010,2011
|
10.1103/PhysRevD.83.104010
|
KEK-TH-1431
|
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We study the method for generating the initial data of black hole systems in
Gauss-Bonnet (GB) gravity. The initial data are assumed to be momentarily
static and conformally flat. Although the equation for the conformal factor is
highly nonlinear, it is successfully solved by numerical relaxation for
one-black-hole and two-black-hole systems. The common apparent horizon is
studied in the two-black-hole initial data, and the result suggests that the
Penrose inequalities are satisfied in this system. This is the first step for
simulating black hole collisions in higher-curvature theories.
|
[
{
"created": "Wed, 9 Feb 2011 08:39:56 GMT",
"version": "v1"
}
] |
2011-05-10
|
[
[
"Yoshino",
"Hirotaka",
""
]
] |
We study the method for generating the initial data of black hole systems in Gauss-Bonnet (GB) gravity. The initial data are assumed to be momentarily static and conformally flat. Although the equation for the conformal factor is highly nonlinear, it is successfully solved by numerical relaxation for one-black-hole and two-black-hole systems. The common apparent horizon is studied in the two-black-hole initial data, and the result suggests that the Penrose inequalities are satisfied in this system. This is the first step for simulating black hole collisions in higher-curvature theories.
|
0910.5407
|
Nejc Ko\v{s}nik
|
Svjetlana Fajfer, Ilja Dorsner, Jernej F. Kamenik, Nejc Kosnik
|
Search for new physics in charm processes
|
Presented at FLAVIAnet workshop: low energy constraints on extensions
of the Standard model, Kazimierz
|
Acta Phys.Polon.Supp.3:125-130,2010
| null | null |
hep-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Charm procceses are usually not considered to be favorable candidates in the
search for new physics. Recent disagreement between experimental and lattice
QCD results on the D_s decay constant has motivated us to systematically
reinvestigate role of leptoquarks in rare charm meson decays. We include
constrains coming from the light meson decays.
|
[
{
"created": "Wed, 28 Oct 2009 15:37:57 GMT",
"version": "v1"
}
] |
2010-11-02
|
[
[
"Fajfer",
"Svjetlana",
""
],
[
"Dorsner",
"Ilja",
""
],
[
"Kamenik",
"Jernej F.",
""
],
[
"Kosnik",
"Nejc",
""
]
] |
Charm procceses are usually not considered to be favorable candidates in the search for new physics. Recent disagreement between experimental and lattice QCD results on the D_s decay constant has motivated us to systematically reinvestigate role of leptoquarks in rare charm meson decays. We include constrains coming from the light meson decays.
|
0906.1570
|
Claudio Simeone
|
Martin G. Richarte and Claudio Simeone
|
More about thin-shell wormholes associated to cosmic strings
|
8 pages; accepted for publication in Physical Review D
|
Phys.Rev.D79:127502,2009
|
10.1103/PhysRevD.79.127502
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Previous analysis about thin-shell wormholes associated to cosmic strings are
extended. More evidence is found supporting the conjecture that, under
reasonable assumptions about the equations of state of matter on the shell, the
configurations are not stable under radial velocity perturbations.
|
[
{
"created": "Mon, 8 Jun 2009 19:35:09 GMT",
"version": "v1"
}
] |
2009-07-09
|
[
[
"Richarte",
"Martin G.",
""
],
[
"Simeone",
"Claudio",
""
]
] |
Previous analysis about thin-shell wormholes associated to cosmic strings are extended. More evidence is found supporting the conjecture that, under reasonable assumptions about the equations of state of matter on the shell, the configurations are not stable under radial velocity perturbations.
|
0810.1016
|
Lijun Zhu
|
Kaustubh Agashe, Aleksandr Azatov and Lijun Zhu
|
Flavor Violation Tests of Warped/Composite SM in the Two-Site Approach
|
46 pages with 10 figures
| null |
10.1103/PhysRevD.79.056006
|
UMD-PP-08-015
|
hep-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We study flavor violation in the quark sector in a purely 4D, two-site
effective field theory description of the Standard Model and just their first
Kaluza-Klein excitations from a warped extra dimension. The warped 5D framework
can provide solutions to both the Planck-weak and flavor hierarchies of the SM.
It is also related (via the AdS/CFT correspondence) to partial compositeness of
the SM. We focus on the dominant contributions in the two-site model to two
observables which we argue provide the strongest flavor constraints, namely,
epsilon_K and BR(b -> s gamma), where contributions in the two-site model occur
at tree and loop-level, respectively. In particular, we demonstrate that a
"tension" exists between these two observables in the sense that they have
opposite dependence on composite site Yukawa couplings, making it difficult to
decouple flavor-violating effects using this parameter. We choose the size of
the composite site QCD coupling based on the relation of the two-site model to
the 5D model (addressing the Planck-weak hierarchy), where we match the 5D QCD
coupling to the 4D coupling at the loop-level and assuming negligible
tree-level brane-localized kinetic terms. We estimate that a larger size of the
5D gauge coupling is constrained by the requirement of 5D perturbativity. We
find that \sim O(5) TeV mass scale for the new particles in the two-site model
can then be consistent with both observables. We also compare our analysis of
epsilon_K in the two-site model to that in 5D models, including both the cases
of a brane-localized and bulk Higgs.
|
[
{
"created": "Mon, 6 Oct 2008 19:42:19 GMT",
"version": "v1"
},
{
"created": "Fri, 31 Oct 2008 22:05:47 GMT",
"version": "v2"
}
] |
2009-11-13
|
[
[
"Agashe",
"Kaustubh",
""
],
[
"Azatov",
"Aleksandr",
""
],
[
"Zhu",
"Lijun",
""
]
] |
We study flavor violation in the quark sector in a purely 4D, two-site effective field theory description of the Standard Model and just their first Kaluza-Klein excitations from a warped extra dimension. The warped 5D framework can provide solutions to both the Planck-weak and flavor hierarchies of the SM. It is also related (via the AdS/CFT correspondence) to partial compositeness of the SM. We focus on the dominant contributions in the two-site model to two observables which we argue provide the strongest flavor constraints, namely, epsilon_K and BR(b -> s gamma), where contributions in the two-site model occur at tree and loop-level, respectively. In particular, we demonstrate that a "tension" exists between these two observables in the sense that they have opposite dependence on composite site Yukawa couplings, making it difficult to decouple flavor-violating effects using this parameter. We choose the size of the composite site QCD coupling based on the relation of the two-site model to the 5D model (addressing the Planck-weak hierarchy), where we match the 5D QCD coupling to the 4D coupling at the loop-level and assuming negligible tree-level brane-localized kinetic terms. We estimate that a larger size of the 5D gauge coupling is constrained by the requirement of 5D perturbativity. We find that \sim O(5) TeV mass scale for the new particles in the two-site model can then be consistent with both observables. We also compare our analysis of epsilon_K in the two-site model to that in 5D models, including both the cases of a brane-localized and bulk Higgs.
|
1305.5206
|
Javier Mazzitelli
|
Daniel de Florian and Javier Mazzitelli
|
Two-loop virtual corrections to Higgs pair production
| null |
Physics Letters B 724 (2013), pp. 306-309
|
10.1016/j.physletb.2013.06.046
| null |
hep-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We present the two-loop virtual corrections to Standard Model Higgs boson
pair production via gluon fusion $gg\to HH$ in the heavy top quark limit. Based
on this result, we evaluate the corresponding cross section at the LHC at 14
TeV in the next-to-next-to-leading order soft-virtual approximation. We find an
inclusive K-factor of about 2.4, resulting in an increase close to 23% with
respect to the previous available calculation at next-to-leading order. As
expected, we observe a considerable reduction in the renormalization and
factorization scale dependence.
|
[
{
"created": "Wed, 22 May 2013 17:40:28 GMT",
"version": "v1"
},
{
"created": "Fri, 21 Jun 2013 14:00:20 GMT",
"version": "v2"
}
] |
2013-07-12
|
[
[
"de Florian",
"Daniel",
""
],
[
"Mazzitelli",
"Javier",
""
]
] |
We present the two-loop virtual corrections to Standard Model Higgs boson pair production via gluon fusion $gg\to HH$ in the heavy top quark limit. Based on this result, we evaluate the corresponding cross section at the LHC at 14 TeV in the next-to-next-to-leading order soft-virtual approximation. We find an inclusive K-factor of about 2.4, resulting in an increase close to 23% with respect to the previous available calculation at next-to-leading order. As expected, we observe a considerable reduction in the renormalization and factorization scale dependence.
|
hep-ph/0407085
|
Marco Radici
|
Marco Radici
|
How to Study Quark Spin without Spin
|
invited talk at 2nd PANDA Physics Workshop, Frascati, March 18-19,
2004; 23 pages, 13 figures, Frascati Physics Series style file included;
revised version including more references
| null | null | null |
hep-ph
| null |
I review the most important single- and double-spin asymmetries that allow
for the extraction of transversity and other chiral-odd and/or T-odd parton
densities, necessary to explore the partonic content and the spin structure of
the nucleon. With particular reference to the proposed GSI-HESR facility, I
report on some Monte-Carlo simulations of cross sections and spin asymmetries
for (un)polarized Drell-Yan with protons and antiprotons at the proposed
kinematics for this future facility.
|
[
{
"created": "Wed, 7 Jul 2004 14:24:36 GMT",
"version": "v1"
},
{
"created": "Thu, 15 Jul 2004 09:10:56 GMT",
"version": "v2"
},
{
"created": "Sun, 18 Jul 2004 10:38:14 GMT",
"version": "v3"
}
] |
2007-05-23
|
[
[
"Radici",
"Marco",
""
]
] |
I review the most important single- and double-spin asymmetries that allow for the extraction of transversity and other chiral-odd and/or T-odd parton densities, necessary to explore the partonic content and the spin structure of the nucleon. With particular reference to the proposed GSI-HESR facility, I report on some Monte-Carlo simulations of cross sections and spin asymmetries for (un)polarized Drell-Yan with protons and antiprotons at the proposed kinematics for this future facility.
|
1606.05295
|
Sebasti\'an Bahamonde
|
Sebastian Bahamonde, Mubasher Jamil, Petar Pavlovic, Marko Sossich
|
Cosmological wormholes in $f(R)$ theories of gravity
|
Slighly updated version. Accepted for publication in Physical Review
D
|
Phys. Rev. D 94, 044041 (2016)
|
10.1103/PhysRevD.94.044041
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Motivated by recent proposals of possible wormhole existence in galactic
halos, we analyse the cosmological evolution of wormhole solutions in modified
$f(R)$ gravity. We construct a dynamical wormhole that asymptotically
approaches FLRW universe, with supporting material going to the perfect
isotropic fluid described by the equation of state for radiation and matter
dominated universe respectively. Our analysis is based on an approximation of a
small wormhole - a wormhole that can be treated as matched with the FLRW metric
at some radial coordinate much smaller than the Hubble radius, so that
cosmological boundary conditions are satisfied. With a special interest in
viable wormhole solutions, we refer to the results of reconstruction procedure
and use $f(R)$ functions which lead to the experimentally confirmed
$\Lambda$CDM expansion history of the Universe. Solutions we find imply no need
for exotic matter near the throat of considered wormholes, while in the limit
of $f(R)=R$ this need is always present during radiation and matter dominated
epoch.
|
[
{
"created": "Thu, 16 Jun 2016 18:01:17 GMT",
"version": "v1"
},
{
"created": "Sun, 7 Aug 2016 17:52:25 GMT",
"version": "v2"
}
] |
2016-08-24
|
[
[
"Bahamonde",
"Sebastian",
""
],
[
"Jamil",
"Mubasher",
""
],
[
"Pavlovic",
"Petar",
""
],
[
"Sossich",
"Marko",
""
]
] |
Motivated by recent proposals of possible wormhole existence in galactic halos, we analyse the cosmological evolution of wormhole solutions in modified $f(R)$ gravity. We construct a dynamical wormhole that asymptotically approaches FLRW universe, with supporting material going to the perfect isotropic fluid described by the equation of state for radiation and matter dominated universe respectively. Our analysis is based on an approximation of a small wormhole - a wormhole that can be treated as matched with the FLRW metric at some radial coordinate much smaller than the Hubble radius, so that cosmological boundary conditions are satisfied. With a special interest in viable wormhole solutions, we refer to the results of reconstruction procedure and use $f(R)$ functions which lead to the experimentally confirmed $\Lambda$CDM expansion history of the Universe. Solutions we find imply no need for exotic matter near the throat of considered wormholes, while in the limit of $f(R)=R$ this need is always present during radiation and matter dominated epoch.
|
hep-ph/0009220
|
Wei-Shu Hou
|
George W.S. Hou
|
What Can We Learn from Charmless Rare B Decays - the Past/Next 3 Years
|
6 pages, 2 eps figures included. Invited talk presented at joint
session of the 8th Asia Pacific Physics Conference (APPC 2000) and 3rd ACFA
Workshop on Physics/Detector at the Linear Collider (ACFA-LC3), Taipei,
Taiwan, August 2000
| null |
10.1142/9789812811523_0094
| null |
hep-ph
| null |
A personal perspective is given on physics of charmless rare B decays: 1997
-- 2003.
|
[
{
"created": "Tue, 19 Sep 2000 13:43:33 GMT",
"version": "v1"
}
] |
2017-08-23
|
[
[
"Hou",
"George W. S.",
""
]
] |
A personal perspective is given on physics of charmless rare B decays: 1997 -- 2003.
|
2206.13233
|
Mohammed Khalil
|
Mohammed Khalil, Raissa F. P. Mendes, N\'estor Ortiz, Jan Steinhoff
|
Effective-action model for dynamical scalarization beyond the adiabatic
approximation
|
15 pages, 11 figures. v2: matches published version
| null |
10.1103/PhysRevD.106.104016
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In certain scalar-field extensions to general relativity, scalar charges can
develop on compact objects in an inspiraling binary -- an effect known as
dynamical scalarization. This effect can be modeled using
effective-field-theory methods applied to the binary within the post-Newtonian
approximation. Past analytic investigations focused on the adiabatic (or
quasi-stationary) case for quasi-circular orbits. In this work, we explore the
full dynamical evolution around the phase transition to the scalarized regime.
This allows for generic (eccentric) orbits and to quantify nonadiabatic (e.g.,
oscillatory) behavior during the phase transition. We also find that even in
the circular-orbit case, the onset of scalarization can only be predicted
reliably when taking the full dynamics into account, i.e., the adiabatic
approximation is not appropriate. Our results pave the way for accurate
post-Newtonian predictions for dynamical scalarization effects in gravitational
waves from compact binaries.
|
[
{
"created": "Mon, 27 Jun 2022 12:25:41 GMT",
"version": "v1"
},
{
"created": "Wed, 2 Nov 2022 16:12:14 GMT",
"version": "v2"
}
] |
2022-11-23
|
[
[
"Khalil",
"Mohammed",
""
],
[
"Mendes",
"Raissa F. P.",
""
],
[
"Ortiz",
"Néstor",
""
],
[
"Steinhoff",
"Jan",
""
]
] |
In certain scalar-field extensions to general relativity, scalar charges can develop on compact objects in an inspiraling binary -- an effect known as dynamical scalarization. This effect can be modeled using effective-field-theory methods applied to the binary within the post-Newtonian approximation. Past analytic investigations focused on the adiabatic (or quasi-stationary) case for quasi-circular orbits. In this work, we explore the full dynamical evolution around the phase transition to the scalarized regime. This allows for generic (eccentric) orbits and to quantify nonadiabatic (e.g., oscillatory) behavior during the phase transition. We also find that even in the circular-orbit case, the onset of scalarization can only be predicted reliably when taking the full dynamics into account, i.e., the adiabatic approximation is not appropriate. Our results pave the way for accurate post-Newtonian predictions for dynamical scalarization effects in gravitational waves from compact binaries.
|
1201.5498
|
Luca Fabbri
|
Luca Fabbri, Stefano Vignolo
|
A modified theory of gravity with torsion and its applications to
cosmology and particle physics
|
21 pages
|
Int.J.Theor.Phys.51, 3186-3207 (2012)
|
10.1007/s10773-012-1199-2
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper we consider the most general least-order derivative theory of
gravity in which not only curvature but also torsion is explicitly present in
the Lagrangian, and where all independent fields have their own coupling
constant: we will apply this theory to the case of ELKO fields, which is the
acronym of the German \textit{Eigenspinoren des LadungsKonjugationsOperators}
designating eigenspinors of the charge conjugation operator, and thus they are
a Majorana-like special type of spinors; and to the Dirac fields, the most
general type of spinors. We shall see that because torsion has a coupling
constant that is still undetermined, the ELKO and Dirac field equations are
endowed with self-interactions whose coupling constant is undetermined: we
discuss different applications according to the value of the coupling constants
and the different properties that consequently follow. We highlight that in
this approach, the ELKO and Dirac field's self-interactions depend on the
coupling constant as a parameter that may even make these non-linearities
manifest at subatomic scales.
|
[
{
"created": "Thu, 26 Jan 2012 12:15:20 GMT",
"version": "v1"
},
{
"created": "Wed, 30 May 2012 11:50:14 GMT",
"version": "v2"
},
{
"created": "Wed, 24 Apr 2013 14:22:01 GMT",
"version": "v3"
}
] |
2013-04-25
|
[
[
"Fabbri",
"Luca",
""
],
[
"Vignolo",
"Stefano",
""
]
] |
In this paper we consider the most general least-order derivative theory of gravity in which not only curvature but also torsion is explicitly present in the Lagrangian, and where all independent fields have their own coupling constant: we will apply this theory to the case of ELKO fields, which is the acronym of the German \textit{Eigenspinoren des LadungsKonjugationsOperators} designating eigenspinors of the charge conjugation operator, and thus they are a Majorana-like special type of spinors; and to the Dirac fields, the most general type of spinors. We shall see that because torsion has a coupling constant that is still undetermined, the ELKO and Dirac field equations are endowed with self-interactions whose coupling constant is undetermined: we discuss different applications according to the value of the coupling constants and the different properties that consequently follow. We highlight that in this approach, the ELKO and Dirac field's self-interactions depend on the coupling constant as a parameter that may even make these non-linearities manifest at subatomic scales.
|
1711.09772
|
Lobsang Dhargyal
|
Lobsang Dhargyal
|
A simple model to explain the observed muon sector anomalies and small
neutrino masses
|
similar to the one accepted at Journal of Physics G: Nuclear and
Particle Physics
| null | null | null |
hep-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Since its inception, no decisive departure from the predictions of Standard
Model (SM) has been reported. But recently various experiments have observed
few hints of possible departure from SM predictions in lepton flavor
universality observables such as $R_{K^{(*)}}$, $P_{5}^{'}$, muon (g-2),
$R(D^{(*)})$ etc. Many of these observable where deviation from SM in the range
of (2-4)$\sigma$ were observed are related to muon ($\mu$) lepton. So these
deviations may be some hint of a possible New Physics (NP) in the muon sector.
In this work we extend the SM by introducing two SM singlet heavy charged
leptons ($F_{e},\ F_{\mu}$) whose left handed components are charged under a
new $U(1)_{F}$ gauge symmetry, one color triplet lepto-quark ($\phi_{Q}$)
doublet under $SU(2)_{L}$, one inert Higgs doublet ($\phi_{l}$), three very
heavy Majorana neutrinos ($N_{iR}$), all of which are odd under a $Z_{2}$
discrete symmetry. One more scalar ($\phi$) charged only under the $U(1)_{F}$
whose VEV give masses to the $U(1)_{F}$ gauge boson as well as the heavy
leptons. With these new particles, we show that the observed anomalies in the
muon sector as well as small neutrino masses can be explained with taking into
account all the other experimental and theoretical constrains till date.
|
[
{
"created": "Mon, 27 Nov 2017 15:41:58 GMT",
"version": "v1"
},
{
"created": "Tue, 28 Nov 2017 14:32:32 GMT",
"version": "v2"
},
{
"created": "Sun, 28 Jan 2018 13:09:33 GMT",
"version": "v3"
},
{
"created": "Thu, 1 Nov 2018 15:29:26 GMT",
"version": "v4"
},
{
"created": "Thu, 5 Sep 2019 14:44:44 GMT",
"version": "v5"
}
] |
2019-09-06
|
[
[
"Dhargyal",
"Lobsang",
""
]
] |
Since its inception, no decisive departure from the predictions of Standard Model (SM) has been reported. But recently various experiments have observed few hints of possible departure from SM predictions in lepton flavor universality observables such as $R_{K^{(*)}}$, $P_{5}^{'}$, muon (g-2), $R(D^{(*)})$ etc. Many of these observable where deviation from SM in the range of (2-4)$\sigma$ were observed are related to muon ($\mu$) lepton. So these deviations may be some hint of a possible New Physics (NP) in the muon sector. In this work we extend the SM by introducing two SM singlet heavy charged leptons ($F_{e},\ F_{\mu}$) whose left handed components are charged under a new $U(1)_{F}$ gauge symmetry, one color triplet lepto-quark ($\phi_{Q}$) doublet under $SU(2)_{L}$, one inert Higgs doublet ($\phi_{l}$), three very heavy Majorana neutrinos ($N_{iR}$), all of which are odd under a $Z_{2}$ discrete symmetry. One more scalar ($\phi$) charged only under the $U(1)_{F}$ whose VEV give masses to the $U(1)_{F}$ gauge boson as well as the heavy leptons. With these new particles, we show that the observed anomalies in the muon sector as well as small neutrino masses can be explained with taking into account all the other experimental and theoretical constrains till date.
|
1109.6201
|
Matteo Luca Ruggiero
|
Angelo Tartaglia, Matteo Luca Ruggiero, Emiliano Capolongo
|
A relativistic navigation system for space
|
11 pages
|
Acta Futura 4 (2011) 33.40
|
10.2420/AF04.2011.33
| null |
gr-qc physics.space-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We present here a method for the relativistic positioning in spacetime based
on the reception of pulses from sources of electromagnetic signals whose
worldline is known. The method is based on the use of a four-dimensional grid
covering the whole spacetime and made of the null hypersurfaces representing
the propagating pulses. In our first approach to the problem of positioning we
consider radio-pulsars at infinity as primary sources of the required signals.
The reason is that, besides being very good clocks, pulsars can be considered
as being fixed stars for reasonably long times. The positioning is obtained
linearizing the worldline of the observer for times of the order of a few
periods of the signals. We present an exercise where the use of our method
applied to the signals from four real pulsars permits the reconstruction of the
motion of the Earth with respect to the fixed stars during three days. The
uncertainties and the constraints of the method are discussed and the
possibilities of using moving artificial sources carried around by celestial
bodies or spacecrafts in the Solar System is also discussed.
|
[
{
"created": "Wed, 28 Sep 2011 13:34:12 GMT",
"version": "v1"
}
] |
2011-09-29
|
[
[
"Tartaglia",
"Angelo",
""
],
[
"Ruggiero",
"Matteo Luca",
""
],
[
"Capolongo",
"Emiliano",
""
]
] |
We present here a method for the relativistic positioning in spacetime based on the reception of pulses from sources of electromagnetic signals whose worldline is known. The method is based on the use of a four-dimensional grid covering the whole spacetime and made of the null hypersurfaces representing the propagating pulses. In our first approach to the problem of positioning we consider radio-pulsars at infinity as primary sources of the required signals. The reason is that, besides being very good clocks, pulsars can be considered as being fixed stars for reasonably long times. The positioning is obtained linearizing the worldline of the observer for times of the order of a few periods of the signals. We present an exercise where the use of our method applied to the signals from four real pulsars permits the reconstruction of the motion of the Earth with respect to the fixed stars during three days. The uncertainties and the constraints of the method are discussed and the possibilities of using moving artificial sources carried around by celestial bodies or spacecrafts in the Solar System is also discussed.
|
1402.4363
|
Francisco Lobo
|
Tiberiu Harko, Francisco S. N. Lobo, M. K. Mak
|
A Riccati equation based approach to isotropic scalar field cosmologies
|
7 pages, 5 figures. V2: minor changes and additions, matches
published version in the International Journal of Modern Physics D
|
Int.J.Mod.Phys.D23:1450063,2014
|
10.1142/S0218271814500631
| null |
gr-qc astro-ph.CO math-ph math.MP
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Gravitationally coupled scalar fields $\phi $, distinguished by the choice of
an effective self-interaction potential $V(\phi )$, simulating a temporarily
non-vanishing cosmological term, can generate both inflation and late time
acceleration. In scalar field cosmological models the evolution of the Hubble
function is determined, in terms of the interaction potential, by a Riccati
type equation. In the present work we investigate scalar field cosmological
models that can be obtained as solutions of the Riccati evolution equation for
the Hubble function. Four exact integrability cases of the field equations are
presented, representing classes of general solutions of the Riccati evolution
equation. The solutions correspond to cosmological models in which the Hubble
function is proportional to the scalar field potential plus a linearly
decreasing function of time, models with the time variation of the scalar field
potential proportional to the potential minus its square, models in which the
potential is the sum of an arbitrary function and the square of the function
integral, and models in which the potential is the sum of an arbitrary function
and the derivative of its square root, respectively. The cosmological
properties of all models are investigated in detail, and it is shown that they
can describe the inflationary or the late accelerating phase in the evolution
of the Universe
|
[
{
"created": "Tue, 18 Feb 2014 14:55:03 GMT",
"version": "v1"
},
{
"created": "Sat, 24 May 2014 13:33:04 GMT",
"version": "v2"
}
] |
2014-05-27
|
[
[
"Harko",
"Tiberiu",
""
],
[
"Lobo",
"Francisco S. N.",
""
],
[
"Mak",
"M. K.",
""
]
] |
Gravitationally coupled scalar fields $\phi $, distinguished by the choice of an effective self-interaction potential $V(\phi )$, simulating a temporarily non-vanishing cosmological term, can generate both inflation and late time acceleration. In scalar field cosmological models the evolution of the Hubble function is determined, in terms of the interaction potential, by a Riccati type equation. In the present work we investigate scalar field cosmological models that can be obtained as solutions of the Riccati evolution equation for the Hubble function. Four exact integrability cases of the field equations are presented, representing classes of general solutions of the Riccati evolution equation. The solutions correspond to cosmological models in which the Hubble function is proportional to the scalar field potential plus a linearly decreasing function of time, models with the time variation of the scalar field potential proportional to the potential minus its square, models in which the potential is the sum of an arbitrary function and the square of the function integral, and models in which the potential is the sum of an arbitrary function and the derivative of its square root, respectively. The cosmological properties of all models are investigated in detail, and it is shown that they can describe the inflationary or the late accelerating phase in the evolution of the Universe
|
1010.2869
|
Karl Schilcher
|
N.F. Nasrallah and K. Schilcher
|
New Sum Rule Determination of the Nucleon Mass
|
7 pages
| null | null |
MZ-TH/10-37
|
hep-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
A new QCD calculation of the mass of the nucleon is presented. It makes use
of a polynomial kernel in the dispersion integrals tailored to practically
eliminate the contribution of the unknown 1/2+ and 1/2- continuum. This
approach avoids the arbitrariness and other drawbacks attached to the Borel
kernel used in previous sum rules calculations. Our method yields stable
results for the nucleon mass and coupling for standard values of the
condensates. The prediction of the nucleon mass m_{N}=(0.945 \pm .045) GeV is
in good agreement with experiment.
|
[
{
"created": "Thu, 14 Oct 2010 09:48:05 GMT",
"version": "v1"
},
{
"created": "Tue, 2 Nov 2010 10:38:49 GMT",
"version": "v2"
}
] |
2010-11-03
|
[
[
"Nasrallah",
"N. F.",
""
],
[
"Schilcher",
"K.",
""
]
] |
A new QCD calculation of the mass of the nucleon is presented. It makes use of a polynomial kernel in the dispersion integrals tailored to practically eliminate the contribution of the unknown 1/2+ and 1/2- continuum. This approach avoids the arbitrariness and other drawbacks attached to the Borel kernel used in previous sum rules calculations. Our method yields stable results for the nucleon mass and coupling for standard values of the condensates. The prediction of the nucleon mass m_{N}=(0.945 \pm .045) GeV is in good agreement with experiment.
|
2212.13683
|
Ruitian Li
|
Ruitian Li, Dazhuang He, Xuan Luo, Hao Sun
|
Exploring the molecular scenario of X(4160)
|
8 pages,8 figures
| null | null | null |
hep-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this work, we investigate the decays of meson $X(4160)$ which is
considered as a hadronic molecule states of $I^GJ^{PC}=0^+2^{++}$. By using the
effective lagrangian approach, we calculate the widths of $X(4160)\to
J/\psi\phi$ and $X(4160)\to D^*\bar{D}^*$ through the triangle loop mechanism
in the molecular scenario. Based on the compositeness condition, the coupling
between $X(4160)$ and the $D_s^*\bar{D}_s^*$ molecular state is determined. The
other coupling constants used are determined phenomenologically. The
calculation of the decay widths shows that the $J/\psi \phi$ decay mode has a
larger branching ratio. These predictions can be seen as a test for the
charmonium assignment of $X(4160)$.
|
[
{
"created": "Wed, 28 Dec 2022 03:40:26 GMT",
"version": "v1"
},
{
"created": "Fri, 17 Feb 2023 01:59:53 GMT",
"version": "v2"
}
] |
2023-02-20
|
[
[
"Li",
"Ruitian",
""
],
[
"He",
"Dazhuang",
""
],
[
"Luo",
"Xuan",
""
],
[
"Sun",
"Hao",
""
]
] |
In this work, we investigate the decays of meson $X(4160)$ which is considered as a hadronic molecule states of $I^GJ^{PC}=0^+2^{++}$. By using the effective lagrangian approach, we calculate the widths of $X(4160)\to J/\psi\phi$ and $X(4160)\to D^*\bar{D}^*$ through the triangle loop mechanism in the molecular scenario. Based on the compositeness condition, the coupling between $X(4160)$ and the $D_s^*\bar{D}_s^*$ molecular state is determined. The other coupling constants used are determined phenomenologically. The calculation of the decay widths shows that the $J/\psi \phi$ decay mode has a larger branching ratio. These predictions can be seen as a test for the charmonium assignment of $X(4160)$.
|
1606.06358
|
Henry Lamm IV
|
Henry Lamm, Richard Lebed
|
High Resolution Nonperturbative Light-Front Simulations of the True
Muonium Atom
|
12 pages, 5 figures, Matches PRD version except for additional
references
|
Phys. Rev. D 94, 016004 (2016)
|
10.1103/PhysRevD.94.016004
| null |
hep-ph nucl-th physics.comp-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Through the development of a parallel code called TMSWIFT, an extensive
light-front quantization study of the nonperturbative spectrum of the bound
state $(\mu^+\mu^-)$, true muonium, has been performed. Using Pad\'{e}
approximants, it has been possible to extract continuum and infinite-cutoff
limits for the singlet and triplet states for a range of values of the coupling
constant $\alpha$. This data set allows for an investigation of the $\alpha$
dependence of the light-front spectra, the results of which are compared to
standard calculations. Decay constants have also been obtained. Improved
calculations have been undertaken for the energy shifts due to the presence of
a second, lighter flavor ($e$). Finally, initial results for three-flavor ($e$,
$\mu$, $\tau$) calculations are presented.
|
[
{
"created": "Mon, 20 Jun 2016 23:08:18 GMT",
"version": "v1"
},
{
"created": "Tue, 19 Jul 2016 22:55:50 GMT",
"version": "v2"
},
{
"created": "Thu, 11 Aug 2016 16:00:04 GMT",
"version": "v3"
}
] |
2016-08-12
|
[
[
"Lamm",
"Henry",
""
],
[
"Lebed",
"Richard",
""
]
] |
Through the development of a parallel code called TMSWIFT, an extensive light-front quantization study of the nonperturbative spectrum of the bound state $(\mu^+\mu^-)$, true muonium, has been performed. Using Pad\'{e} approximants, it has been possible to extract continuum and infinite-cutoff limits for the singlet and triplet states for a range of values of the coupling constant $\alpha$. This data set allows for an investigation of the $\alpha$ dependence of the light-front spectra, the results of which are compared to standard calculations. Decay constants have also been obtained. Improved calculations have been undertaken for the energy shifts due to the presence of a second, lighter flavor ($e$). Finally, initial results for three-flavor ($e$, $\mu$, $\tau$) calculations are presented.
|
1308.2383
|
Shahram Jalalzadeh
|
M. Hashemi, S. Jalalzadeh and S. Vasheghani Farahani
|
Hawking temperature and the emergent cosmic space
|
9 pages, many improvements, to appear in Gen. Relativ. Gravit
| null | null | null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The aim of this work is to model the evolution of the cosmic space based on
thermodynamical parameters. The universe is considered to have an apparent
horizon radius with a Kodama-Hayward temperature assigned to it. The method is
founded on the fact proposed by Padmanabhan [1,2] that the subtraction of the
surface and bulk degrees of freedom provides information on the cosmic space
emergence. The fact of the matter is that in this approach the Raychaudhuri
equation could even be obtained by the consideration of only thermodynamical
parameters. As such, the standard general relativity is taken as the starting
point where by implementing the standard cosmological equations we obtain a
generalized evolutionary equation supporting emergence of the cosmic space. The
method proposed in this work would provide basis for other cosmological models
to have an emergent perspective.
|
[
{
"created": "Sun, 11 Aug 2013 11:49:07 GMT",
"version": "v1"
},
{
"created": "Sun, 29 Mar 2015 19:49:15 GMT",
"version": "v2"
}
] |
2015-03-31
|
[
[
"Hashemi",
"M.",
""
],
[
"Jalalzadeh",
"S.",
""
],
[
"Farahani",
"S. Vasheghani",
""
]
] |
The aim of this work is to model the evolution of the cosmic space based on thermodynamical parameters. The universe is considered to have an apparent horizon radius with a Kodama-Hayward temperature assigned to it. The method is founded on the fact proposed by Padmanabhan [1,2] that the subtraction of the surface and bulk degrees of freedom provides information on the cosmic space emergence. The fact of the matter is that in this approach the Raychaudhuri equation could even be obtained by the consideration of only thermodynamical parameters. As such, the standard general relativity is taken as the starting point where by implementing the standard cosmological equations we obtain a generalized evolutionary equation supporting emergence of the cosmic space. The method proposed in this work would provide basis for other cosmological models to have an emergent perspective.
|
gr-qc/0001078
|
Guillermo Arreaga
|
Guillermo Arreaga (CINVESTAV-IPN), Inyong Cho (Emory Univ.) and Jemal
Guven (ICN-UNAM)
|
Stability of self-gravitating magnetic monopoles
|
19 pages, RevTex two cols., 11 eps figs. Submitted to Phys. Rev. D
|
Phys.Rev. D62 (2000) 043520
|
10.1103/PhysRevD.62.043520
| null |
gr-qc
| null |
The stability of a spherically symmetric self-gravitating magnetic monopole
is examined in the thin wall approximation: modeling the interior false vacuum
as a region of de Sitter space; the exterior as an asymptotically flat region
of the Reissner-Nordstr\"om geometry; and the boundary separating the two as a
charged domain wall. There remains only to determine how the wall gets embedded
in these two geometries. In this approximation, the ratio $k$ of the false
vacuum to surface energy densities is a measure of the symmetry breaking scale
$\eta$. Solutions are characterized by this ratio, the charge on the wall $Q$,
and the value of the conserved total energy $M$. We find that for each fixed
$k$ and $Q$ up to some critical value, there exists a unique globally static
solution, with $M\simeq Q^{3/2}$; any stable radial excitation has $M$ bounded
above by $Q$, the value assumed in an extremal Reissner-Nordstr\"om geometry
and these are the only solutions with $M<Q$. As $M$ is raised above $Q$ a black
hole forms in the exterior: (i) for low $Q$ or $k$, the wall is crushed; (ii)
for higher values, it oscillates inside the black hole. If the mass is not too
high these `collapsing' solutions co-exist with an inflating bounce; (iii) for
$k$, $Q$ or $M$ outside the above regimes, there is a unique inflating
solution. In case (i) the course of the bounce lies within a single
asymptotically flat region (AFR) and it resembles closely the bounce exhibited
by a false vacuum bubble (with Q=0). In cases (ii) and (iii) the course of the
bounce spans two consecutive AFRs.
|
[
{
"created": "Tue, 25 Jan 2000 01:30:45 GMT",
"version": "v1"
}
] |
2009-10-31
|
[
[
"Arreaga",
"Guillermo",
"",
"CINVESTAV-IPN"
],
[
"Cho",
"Inyong",
"",
"Emory Univ."
],
[
"Guven",
"Jemal",
"",
"ICN-UNAM"
]
] |
The stability of a spherically symmetric self-gravitating magnetic monopole is examined in the thin wall approximation: modeling the interior false vacuum as a region of de Sitter space; the exterior as an asymptotically flat region of the Reissner-Nordstr\"om geometry; and the boundary separating the two as a charged domain wall. There remains only to determine how the wall gets embedded in these two geometries. In this approximation, the ratio $k$ of the false vacuum to surface energy densities is a measure of the symmetry breaking scale $\eta$. Solutions are characterized by this ratio, the charge on the wall $Q$, and the value of the conserved total energy $M$. We find that for each fixed $k$ and $Q$ up to some critical value, there exists a unique globally static solution, with $M\simeq Q^{3/2}$; any stable radial excitation has $M$ bounded above by $Q$, the value assumed in an extremal Reissner-Nordstr\"om geometry and these are the only solutions with $M<Q$. As $M$ is raised above $Q$ a black hole forms in the exterior: (i) for low $Q$ or $k$, the wall is crushed; (ii) for higher values, it oscillates inside the black hole. If the mass is not too high these `collapsing' solutions co-exist with an inflating bounce; (iii) for $k$, $Q$ or $M$ outside the above regimes, there is a unique inflating solution. In case (i) the course of the bounce lies within a single asymptotically flat region (AFR) and it resembles closely the bounce exhibited by a false vacuum bubble (with Q=0). In cases (ii) and (iii) the course of the bounce spans two consecutive AFRs.
|
1703.09365
|
Jing-Bo Wang
|
Jingbo Wang
|
Black hole as topological insulator (I): the BTZ black hole case
|
7 pages, title changed, adding a section to discuss the coupling with
electromagnetic field
| null | null | null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Black holes are extraordinary massive objects which can be described
classically by general relativity, and topological insulators are new orders of
matter that could be use to built a topological quantum computer. They seem to
be different objects, but in this paper, we claim that the black hole can be
considered as kind of topological insulator. For BTZ black hole in three
dimensional $AdS_3$ spacetime we give two evidences to support this claim: the
first evidence comes from the black hole "membrane paradigm", which says that
the horizon of black hole behaves like an electrical conductor. On the other
hand, the vacuum can be considered as an insulator. The second evidence comes
from the fact that the horizon of BTZ black hole can support two chiral
massless scalar field with opposite chirality. Those are two key properties of
2D topological insulator. We also consider the coupling with the
electromagnetic field to show that the boundary modes can conduct the
electricity. For higher dimensional black hole the first evidence is still
valid. So we conjecture that the higher dimensional black hole can also be
considered as higher dimensional topological insulators. This conjecture will
have far-reaching influences on our understanding of quantum black hole and the
nature of gravity.
|
[
{
"created": "Tue, 28 Mar 2017 01:23:54 GMT",
"version": "v1"
},
{
"created": "Tue, 19 Dec 2017 01:05:08 GMT",
"version": "v2"
}
] |
2017-12-20
|
[
[
"Wang",
"Jingbo",
""
]
] |
Black holes are extraordinary massive objects which can be described classically by general relativity, and topological insulators are new orders of matter that could be use to built a topological quantum computer. They seem to be different objects, but in this paper, we claim that the black hole can be considered as kind of topological insulator. For BTZ black hole in three dimensional $AdS_3$ spacetime we give two evidences to support this claim: the first evidence comes from the black hole "membrane paradigm", which says that the horizon of black hole behaves like an electrical conductor. On the other hand, the vacuum can be considered as an insulator. The second evidence comes from the fact that the horizon of BTZ black hole can support two chiral massless scalar field with opposite chirality. Those are two key properties of 2D topological insulator. We also consider the coupling with the electromagnetic field to show that the boundary modes can conduct the electricity. For higher dimensional black hole the first evidence is still valid. So we conjecture that the higher dimensional black hole can also be considered as higher dimensional topological insulators. This conjecture will have far-reaching influences on our understanding of quantum black hole and the nature of gravity.
|
2307.04071
|
Adriano Barros
|
Adriano Barros and Carlos Romero
|
Homogeneous Cosmological Models in Weyl's Geometrical Scalar-Tensor
Theory
|
20 pages, 3 figures
|
Universe 9 (2023) 283
|
10.3390/universe9060283
| null |
gr-qc
|
http://creativecommons.org/licenses/by-nc-sa/4.0/
|
In this paper, we consider homogeneous cosmological solutions in the context
of the Weyl geometrical scalar-tensor theory. Firstly, we exhibit an
anisotropic Kasner type solution taking advantage of some similarities between
this theory and the Brans-Dicke theory. Next, we consider an isotropic model
with a flat spatial section sourced by matter configurations described by a
perfect fluid. In this model, we obtain an analytical solution for the stiff
matter case. For other cases, we carry out a complete qualitative analysis
theory to investigate the general behaviour of the solutions, presenting some
possible scenarios. In this work, we do not consider the presence of the
cosmological constant nor do we take any potential of the scalar field into
account. Because of this, we do not find any solution describing the
acceleration of the universe.
|
[
{
"created": "Sun, 9 Jul 2023 00:39:59 GMT",
"version": "v1"
}
] |
2023-07-11
|
[
[
"Barros",
"Adriano",
""
],
[
"Romero",
"Carlos",
""
]
] |
In this paper, we consider homogeneous cosmological solutions in the context of the Weyl geometrical scalar-tensor theory. Firstly, we exhibit an anisotropic Kasner type solution taking advantage of some similarities between this theory and the Brans-Dicke theory. Next, we consider an isotropic model with a flat spatial section sourced by matter configurations described by a perfect fluid. In this model, we obtain an analytical solution for the stiff matter case. For other cases, we carry out a complete qualitative analysis theory to investigate the general behaviour of the solutions, presenting some possible scenarios. In this work, we do not consider the presence of the cosmological constant nor do we take any potential of the scalar field into account. Because of this, we do not find any solution describing the acceleration of the universe.
|
gr-qc/9905090
|
David Wiltshire
|
D.L. Wiltshire
|
Wave functions for arbitrary operator ordering in the de Sitter
minisuperspace approximation
|
12 pages, revTeX-3.1
|
Gen.Rel.Grav.32:515-528,2000
|
10.1023/A:1001932502138
|
ADP-99-22/M81
|
gr-qc astro-ph hep-th
| null |
We derive exact series solutions for the Wheeler-DeWitt equation
corresponding to a spatially closed Friedmann-Robertson-Walker universe with
cosmological constant for arbitrary operator ordering of the scale factor of
the universe. The resulting wave functions are those relevant to the
approximation which has been widely used in two-dimensional minisuperspace
models with an inflationary scalar field for the purpose of predicting the
period of inflation which results from competing boundary condition proposals
for the wave function of the universe. The problem that Vilenkin's tunneling
wave function is not normalizable for general operator orderings, is shown to
persist for other values of the spatial curvature, and when additional matter
degrees of freedom such as radiation are included.
|
[
{
"created": "Mon, 24 May 1999 07:55:49 GMT",
"version": "v1"
}
] |
2008-11-26
|
[
[
"Wiltshire",
"D. L.",
""
]
] |
We derive exact series solutions for the Wheeler-DeWitt equation corresponding to a spatially closed Friedmann-Robertson-Walker universe with cosmological constant for arbitrary operator ordering of the scale factor of the universe. The resulting wave functions are those relevant to the approximation which has been widely used in two-dimensional minisuperspace models with an inflationary scalar field for the purpose of predicting the period of inflation which results from competing boundary condition proposals for the wave function of the universe. The problem that Vilenkin's tunneling wave function is not normalizable for general operator orderings, is shown to persist for other values of the spatial curvature, and when additional matter degrees of freedom such as radiation are included.
|
1510.09113
|
Auttakit Chatrabhuti
|
Auttakit Chatrabhuti, Vicharit Yingcharoenrat and Phongpichit Channuie
|
Starobinsky Model in Rainbow Gravity
|
10 pages, 3 figures. v2: corrections and improvement, version to
appear in PRD
|
Phys. Rev. D93 (2016) 043515
|
10.1103/PhysRevD.93.043515
| null |
gr-qc astro-ph.CO
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper, we study the Starobinsky model of inflation in the context of
gravity's rainbow theory. We propose that gravity rainbow functions can be
written in the power-law form of the Hubble parameter. We present a detailed
derivation of the spectral index of curvature perturbation and the
tensor-to-scalar ratio and compare the predictions of our models with Planck
2015 data. We discover that in order to be consistent with Planck data up to
$2\sigma$ C.L., the viable values of $N_{k}$ $e$-folds would satisfy
$42\lesssim N_{k}\lesssim 87$ and the rainbow parameter $\lambda$ is nicely
constrained to be $\lambda \lesssim6.0$.
|
[
{
"created": "Fri, 30 Oct 2015 15:08:47 GMT",
"version": "v1"
},
{
"created": "Thu, 4 Feb 2016 14:48:14 GMT",
"version": "v2"
}
] |
2016-02-11
|
[
[
"Chatrabhuti",
"Auttakit",
""
],
[
"Yingcharoenrat",
"Vicharit",
""
],
[
"Channuie",
"Phongpichit",
""
]
] |
In this paper, we study the Starobinsky model of inflation in the context of gravity's rainbow theory. We propose that gravity rainbow functions can be written in the power-law form of the Hubble parameter. We present a detailed derivation of the spectral index of curvature perturbation and the tensor-to-scalar ratio and compare the predictions of our models with Planck 2015 data. We discover that in order to be consistent with Planck data up to $2\sigma$ C.L., the viable values of $N_{k}$ $e$-folds would satisfy $42\lesssim N_{k}\lesssim 87$ and the rainbow parameter $\lambda$ is nicely constrained to be $\lambda \lesssim6.0$.
|
2006.14335
|
Victor Goncalves
|
A. V. Giannini, V.P. Goncalves, P.V.R.G. Silva
|
Thermal radiation and inclusive production in the running coupling $k_T$
-- factorization approach
|
8 pages, 4 figures, 1 table
| null |
10.1140/epja/s10050-021-00350-w
| null |
hep-ph nucl-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The characteristics of the thermal radiation are investigated using a two -
component model, with the hard component being described by the Color Glass
Condensate formalism. The inclusive transverse momentum spectra of charged
hadrons produced in proton - proton and proton - nucleus collisions at LHC
energies and large - $p_T$ are estimated using the running coupling $k_T$ -
factorization formula and the solution of the Balitsky - Kovchegov equation.
Our results indicate that the thermal term is necessary to describe the
experimental data and that the effective thermal temperature has an energy
dependence similar to the saturation scale. We demonstrate that the enhancement
of the thermal temperature in $pPb$ collisions is consistent with that
predicted by the saturation scale.
|
[
{
"created": "Thu, 25 Jun 2020 12:16:52 GMT",
"version": "v1"
}
] |
2021-02-24
|
[
[
"Giannini",
"A. V.",
""
],
[
"Goncalves",
"V. P.",
""
],
[
"Silva",
"P. V. R. G.",
""
]
] |
The characteristics of the thermal radiation are investigated using a two - component model, with the hard component being described by the Color Glass Condensate formalism. The inclusive transverse momentum spectra of charged hadrons produced in proton - proton and proton - nucleus collisions at LHC energies and large - $p_T$ are estimated using the running coupling $k_T$ - factorization formula and the solution of the Balitsky - Kovchegov equation. Our results indicate that the thermal term is necessary to describe the experimental data and that the effective thermal temperature has an energy dependence similar to the saturation scale. We demonstrate that the enhancement of the thermal temperature in $pPb$ collisions is consistent with that predicted by the saturation scale.
|
hep-ph/0207252
|
Jacques Soffer
|
Jacques Soffer and Oleg V. Teryaev
|
Bjorken sum rule at low Q^2
|
8 pages, 2 eps figures
|
Phys.Lett. B545 (2002) 323-328
|
10.1016/S0370-2693(02)02617-5
|
CPT-2002/P.4553
|
hep-ph
| null |
A description of the generalized Gerasimov-Drell-Hearn sum rules for proton
and neutron is suggested, using their relation to the Bjorken sum rule. The
results support an earlier conjecture, that the structure function g_T features
a smooth Q^2-dependence, while the structure function g_2 is changing rapidly,
due to the elastic contribution to the Burkhardt-Cottingham sum rule. A
possible violation of this later sum rule is briefly discussed.
|
[
{
"created": "Sat, 20 Jul 2002 08:20:49 GMT",
"version": "v1"
}
] |
2009-11-07
|
[
[
"Soffer",
"Jacques",
""
],
[
"Teryaev",
"Oleg V.",
""
]
] |
A description of the generalized Gerasimov-Drell-Hearn sum rules for proton and neutron is suggested, using their relation to the Bjorken sum rule. The results support an earlier conjecture, that the structure function g_T features a smooth Q^2-dependence, while the structure function g_2 is changing rapidly, due to the elastic contribution to the Burkhardt-Cottingham sum rule. A possible violation of this later sum rule is briefly discussed.
|
hep-ph/9503321
|
Alexander Khodjamirian
|
A. Khodjamirian and R. R\"uckl
|
Heavy Meson Exclusive Decays in the Framework of QCD Sum Rules
|
11 pages, Latex, 3 figures added as uuencoded .ps file, presented by
R. R\"uckl at the 138.WE-Heraeus-Seminar on Heavy Quark Physics, Bad Honnef,
Germany, December 14-16,1994
| null | null |
MPI-PhT/95-19, LMU 05/95
|
hep-ph
| null |
We discuss applications of QCD sum rules on the light-cone to the form
factors of the exclusive transitions $B \rightarrow \pi$ and $D\rightarrow
\pi$, and to the $B^*B \pi$ and $D^*D \pi$ coupling constants. In the light of
our results we examine the pole dominance model for these form factors. A first
estimate is given on the nonfactorizable amplitude of the decay $ B \ra J/\psi
K$.
|
[
{
"created": "Tue, 14 Mar 1995 10:28:18 GMT",
"version": "v1"
}
] |
2016-09-01
|
[
[
"Khodjamirian",
"A.",
""
],
[
"Rückl",
"R.",
""
]
] |
We discuss applications of QCD sum rules on the light-cone to the form factors of the exclusive transitions $B \rightarrow \pi$ and $D\rightarrow \pi$, and to the $B^*B \pi$ and $D^*D \pi$ coupling constants. In the light of our results we examine the pole dominance model for these form factors. A first estimate is given on the nonfactorizable amplitude of the decay $ B \ra J/\psi K$.
|
gr-qc/9701028
|
Philip Gibbs
|
Philip E. Gibbs
|
Covariant Energy-Momentum Conservation In General Relativity
|
12 pages, postscript, no figures, references added
| null | null |
PEG-11-97
|
gr-qc
| null |
A covariant formula for conserved currents of energy, momentum and
angular-momentum is derived from a general form of Noethers theorem applied
directly to the Einstein-Hilbert action of classical general relativity. Energy
conservation in a closed big-bang cosmology is discussed as a special case.
Special care is taken to distinguish between kinematic and dynamic expressions.
|
[
{
"created": "Wed, 8 Jan 1997 18:39:03 GMT",
"version": "v1"
},
{
"created": "Tue, 14 Jan 1997 19:15:02 GMT",
"version": "v2"
},
{
"created": "Fri, 17 Jan 1997 20:44:16 GMT",
"version": "v3"
}
] |
2008-02-03
|
[
[
"Gibbs",
"Philip E.",
""
]
] |
A covariant formula for conserved currents of energy, momentum and angular-momentum is derived from a general form of Noethers theorem applied directly to the Einstein-Hilbert action of classical general relativity. Energy conservation in a closed big-bang cosmology is discussed as a special case. Special care is taken to distinguish between kinematic and dynamic expressions.
|
2012.09721
|
Izabela Babiarz Ms
|
Izabela Babiarz, Wolfgang Sch\"afer and Antoni Szczurek
|
Production of $\eta_{c}(1S,2S)$ in $e^+ e^-$ and $pp$ collisions
|
6 pages, 6 figures, a talk presented by I. Babiarz at 40th
International Conference on High Energy physics - ICHEP2020, July 28 - August
6, 2020, Prague, Czech Republic (virtual meeting)
| null | null | null |
hep-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We derive the light-front wave function (LFWF) representation of the
$\gamma^{\star} \gamma^{\star} \to \eta_{c} (1S),\eta_{c}(2S)$ transition form
factor $F(Q^2_1,Q^2_2)$ for two virtual photons in the initial state. For the
LFWF, we use different models obtained from the solution of the Schr\"odinger
equation for a variety of $c\bar{c}$ potentials. We compare our results to the
BaBar experimental data for the $\eta_{c}(1S)$ transition form factor, for one
real and one virtual photon. We observe that the onset of the asymptotic
behaviour is strongly delayed and discuss applicability of the collinear and/or
massless limit.
In addition, we present a thorough analysis of $\eta_{c}(1S,2S)$ quarkonia
hadroproduction in $k_{\perp}$-factorisation in the framework of the
light-front potential approach for the quarkonium wave function. The off-shell
matrix elements for the $g^{\star} g^{\star} \to \eta_{c} (1S,2S)$ vertices are
derived. We discuss the importance of taking into account the gluon
virtualities. We present the transverse momentum distributions of $\eta_c$ for
several models of the unintegrated gluon distributions. Our calculations are
performed for four distinct parametrizations for the $c\bar{c}$ interaction
potential consistent with the meson spectra. We compare our results for
$\eta_{c}(1S)$ to measurements by the LHCb collaboration and present
predictions for $\eta_{c}(2S)$ production.
|
[
{
"created": "Wed, 9 Dec 2020 15:35:56 GMT",
"version": "v1"
}
] |
2020-12-18
|
[
[
"Babiarz",
"Izabela",
""
],
[
"Schäfer",
"Wolfgang",
""
],
[
"Szczurek",
"Antoni",
""
]
] |
We derive the light-front wave function (LFWF) representation of the $\gamma^{\star} \gamma^{\star} \to \eta_{c} (1S),\eta_{c}(2S)$ transition form factor $F(Q^2_1,Q^2_2)$ for two virtual photons in the initial state. For the LFWF, we use different models obtained from the solution of the Schr\"odinger equation for a variety of $c\bar{c}$ potentials. We compare our results to the BaBar experimental data for the $\eta_{c}(1S)$ transition form factor, for one real and one virtual photon. We observe that the onset of the asymptotic behaviour is strongly delayed and discuss applicability of the collinear and/or massless limit. In addition, we present a thorough analysis of $\eta_{c}(1S,2S)$ quarkonia hadroproduction in $k_{\perp}$-factorisation in the framework of the light-front potential approach for the quarkonium wave function. The off-shell matrix elements for the $g^{\star} g^{\star} \to \eta_{c} (1S,2S)$ vertices are derived. We discuss the importance of taking into account the gluon virtualities. We present the transverse momentum distributions of $\eta_c$ for several models of the unintegrated gluon distributions. Our calculations are performed for four distinct parametrizations for the $c\bar{c}$ interaction potential consistent with the meson spectra. We compare our results for $\eta_{c}(1S)$ to measurements by the LHCb collaboration and present predictions for $\eta_{c}(2S)$ production.
|
1012.3551
|
Dominik Scherer
|
Lars Hofer, Dominik Scherer and Leonardo Vernazza
|
Electroweak penguins in isospin-violating B_s decays
|
Only 2 pages. Presented at ICHEP 2010
| null | null |
TTP10-51
|
hep-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The 2.5 sigma discrepancy between theory and experiment observed in the
difference Delta ACP = ACP(B- --> pi0 K-) - ACP(Bb0 --> pi+ K-) can be
explained by a new electroweak (EW) penguin amplitude. Motivated by this
result, we have analyzed the purely isospin-violating decays B_s --> phi pi0
and B_s phi rho0, which are dominated by EW penguins. Our results extend the
analysis in arXiv:0910.2809 and have recently been published in
arXiv:1011.6319. Here we give a brief overview of the outcome.
|
[
{
"created": "Thu, 16 Dec 2010 10:18:07 GMT",
"version": "v1"
}
] |
2010-12-17
|
[
[
"Hofer",
"Lars",
""
],
[
"Scherer",
"Dominik",
""
],
[
"Vernazza",
"Leonardo",
""
]
] |
The 2.5 sigma discrepancy between theory and experiment observed in the difference Delta ACP = ACP(B- --> pi0 K-) - ACP(Bb0 --> pi+ K-) can be explained by a new electroweak (EW) penguin amplitude. Motivated by this result, we have analyzed the purely isospin-violating decays B_s --> phi pi0 and B_s phi rho0, which are dominated by EW penguins. Our results extend the analysis in arXiv:0910.2809 and have recently been published in arXiv:1011.6319. Here we give a brief overview of the outcome.
|
2406.03096
|
Gerrit Bickendorf
|
Gerrit Bickendorf, Manuel Drees
|
Learning to see R-parity violating scalar top decays
|
13 pages, 9 figures
| null | null | null |
hep-ph hep-ex
|
http://creativecommons.org/licenses/by/4.0/
|
With this article we introduce recent, improved machine learning methods from
computer vision to the problem of event classification in particle physics.
Supersymmetric scalar top decays to top quarks and weak scale bino-like
neutralinos, where the neutralinos decay via the $UDD$ operator to three
quarks, are difficult to search for and therefore weakly constrained. The jet
substructure of the boosted decay products can be used to differentiate signal
from background events. We apply transformer-based computer vision models
CoAtNet and MaxViT to images built from jet constituents and compare the
classification performance to a more classical convolutional neural network
(CNN). We find that results from computer vision translate well onto physics
applications and both transformer-based models perform better than the CNN. By
replacing the CNN with MaxViT we find an improvement of $S/\sqrt{B}$ by a
factor of almost 2 for some neutralino masses. We show that combining this
classifier with additional features results in a strong separation of
background and signal. We also find that replacing a CNN with a MaxViT model in
a simple mock analysis can push the 95% C.L. exclusion limit of stop masses by
about $100$ GeV and $60$ GeV for neutralino masses of $100$ GeV and $500$ GeV.
|
[
{
"created": "Wed, 5 Jun 2024 09:39:15 GMT",
"version": "v1"
}
] |
2024-06-07
|
[
[
"Bickendorf",
"Gerrit",
""
],
[
"Drees",
"Manuel",
""
]
] |
With this article we introduce recent, improved machine learning methods from computer vision to the problem of event classification in particle physics. Supersymmetric scalar top decays to top quarks and weak scale bino-like neutralinos, where the neutralinos decay via the $UDD$ operator to three quarks, are difficult to search for and therefore weakly constrained. The jet substructure of the boosted decay products can be used to differentiate signal from background events. We apply transformer-based computer vision models CoAtNet and MaxViT to images built from jet constituents and compare the classification performance to a more classical convolutional neural network (CNN). We find that results from computer vision translate well onto physics applications and both transformer-based models perform better than the CNN. By replacing the CNN with MaxViT we find an improvement of $S/\sqrt{B}$ by a factor of almost 2 for some neutralino masses. We show that combining this classifier with additional features results in a strong separation of background and signal. We also find that replacing a CNN with a MaxViT model in a simple mock analysis can push the 95% C.L. exclusion limit of stop masses by about $100$ GeV and $60$ GeV for neutralino masses of $100$ GeV and $500$ GeV.
|
2303.00778
|
Andrea Caputo
|
Salvatore Bottaro, Andrea Caputo, Georg Raffelt and Edoardo Vitagliano
|
Stellar limits on scalars from electron-nucleus bremsstrahlung
|
22 pages + appendices, 7 figures. Matches the published version
| null |
10.1088/1475-7516/2023/07/071
|
CERN-TH-2023-035
|
hep-ph astro-ph.SR
|
http://creativecommons.org/publicdomain/zero/1.0/
|
We revisit stellar energy-loss bounds on the Yukawa couplings $g_{\rm B,L}$
of baryophilic and leptophilic scalars $\phi$. The white-dwarf luminosity
function yields $g_{\rm B}\lesssim 7 \times 10^{-13}$ and $g_{\rm L}\lesssim 4
\times 10^{-16}$, based on bremsstrahlung from ${}^{12}{\rm C}$ and
${}^{16}{\rm O}$ collisions with electrons. In models with a Higgs portal, this
also implies a bound on the scalar-Higgs mixing angle $\sin \theta \lesssim 2
\times 10^{-10}$. Our new bounds apply for $m_\phi\lesssim {\rm 1~keV}$ and are
among the most restrictive ones, whereas for $m_\phi\lesssim 0.5\,{\rm eV}$
long-range force measurements dominate. Besides a detailed calculation of the
bremsstrahlung rate for degenerate and semi-relativistic electrons, we prove
with a simple argument that non-relativistic bremsstrahlung by the heavy
partner is suppressed relative to that by the light one by their squared-mass
ratio. This large reduction was overlooked in previous much stronger bounds on
$g_{\rm B}$. In an Appendix, we provide fitting formulas (few percent
precision) for the bremsstrahlung emission of baryophilic and leptophilic
scalars as well as axions for white-dwarf conditions, i.e., degenerate,
semi-relativistic electrons and ion-ion correlations in the ``liquid'' phase.
|
[
{
"created": "Wed, 1 Mar 2023 19:05:41 GMT",
"version": "v1"
},
{
"created": "Thu, 17 Aug 2023 09:43:41 GMT",
"version": "v2"
}
] |
2023-08-21
|
[
[
"Bottaro",
"Salvatore",
""
],
[
"Caputo",
"Andrea",
""
],
[
"Raffelt",
"Georg",
""
],
[
"Vitagliano",
"Edoardo",
""
]
] |
We revisit stellar energy-loss bounds on the Yukawa couplings $g_{\rm B,L}$ of baryophilic and leptophilic scalars $\phi$. The white-dwarf luminosity function yields $g_{\rm B}\lesssim 7 \times 10^{-13}$ and $g_{\rm L}\lesssim 4 \times 10^{-16}$, based on bremsstrahlung from ${}^{12}{\rm C}$ and ${}^{16}{\rm O}$ collisions with electrons. In models with a Higgs portal, this also implies a bound on the scalar-Higgs mixing angle $\sin \theta \lesssim 2 \times 10^{-10}$. Our new bounds apply for $m_\phi\lesssim {\rm 1~keV}$ and are among the most restrictive ones, whereas for $m_\phi\lesssim 0.5\,{\rm eV}$ long-range force measurements dominate. Besides a detailed calculation of the bremsstrahlung rate for degenerate and semi-relativistic electrons, we prove with a simple argument that non-relativistic bremsstrahlung by the heavy partner is suppressed relative to that by the light one by their squared-mass ratio. This large reduction was overlooked in previous much stronger bounds on $g_{\rm B}$. In an Appendix, we provide fitting formulas (few percent precision) for the bremsstrahlung emission of baryophilic and leptophilic scalars as well as axions for white-dwarf conditions, i.e., degenerate, semi-relativistic electrons and ion-ion correlations in the ``liquid'' phase.
|
1506.02716
|
Anita Prapotnik Brdnik Dr.
|
Svjetlana Fajfer, Anita Prapotnik Brdnik
|
Chiral loops in the isospin violating decays of D_{s1}(2460) and
D*_{s0}(2317)
| null |
Phys. Rev. D 92, 074047 (2015)
|
10.1103/PhysRevD.92.074047
| null |
hep-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Positive parity meson states D*_{s0}(2317) and D_{s1}(2460) have masses
slightly below the DK threshold. Therefore, both states can strongly decay only
into isospin violating decays D_{s1}(2460) --> Ds \pi \pi, D_{s1}(2460) --> Ds*
\pi 0 and D*_{s0}(2317) --> Ds \pi 0. The pion states are having rather small
energies, what makes these decays appropriate to study within heavy meson
chiral perturbation theory and calculate loop contributions. The D_{s1}(2460)
--> Ds \pi \pi decays occur only at the loop level. Amplitude is a result of
chiral loop contributions, which then have to be finite. However, in the case
of D_{s1}(2460)--> Ds* \pi 0 and D*_{s0}(2317)--> Ds \pi 0 decays, there is a
tree level contribution. We find that chiral loop contributions might be
important in both cases. The calculated amplitudes are sensitive on the
coupling constant describing the interaction of positive and negative parity
heavy meson multiplets with the light pseudoscalars. The counter-terms
contributions are also present in the amplitudes D_{s1}(2460) --> Ds* \pi 0 and
D*_{s0}(2317) --> Ds \pi 0. We explore experimentally known ratio of the decay
widths for these two decay modes to estimate the size of counter-terms
contributions. We determine decay widths for both decay modes to be Gamma
(D_{s1}(2460) --> Ds \pi + \pi -) = 0.25 keV and Gamma (D_{s1}(2460) --> Ds +
\pi 0 \pi 0 ) = 0.15 keV.
|
[
{
"created": "Mon, 8 Jun 2015 22:21:38 GMT",
"version": "v1"
},
{
"created": "Thu, 29 Oct 2015 22:22:56 GMT",
"version": "v2"
}
] |
2015-11-02
|
[
[
"Fajfer",
"Svjetlana",
""
],
[
"Brdnik",
"Anita Prapotnik",
""
]
] |
Positive parity meson states D*_{s0}(2317) and D_{s1}(2460) have masses slightly below the DK threshold. Therefore, both states can strongly decay only into isospin violating decays D_{s1}(2460) --> Ds \pi \pi, D_{s1}(2460) --> Ds* \pi 0 and D*_{s0}(2317) --> Ds \pi 0. The pion states are having rather small energies, what makes these decays appropriate to study within heavy meson chiral perturbation theory and calculate loop contributions. The D_{s1}(2460) --> Ds \pi \pi decays occur only at the loop level. Amplitude is a result of chiral loop contributions, which then have to be finite. However, in the case of D_{s1}(2460)--> Ds* \pi 0 and D*_{s0}(2317)--> Ds \pi 0 decays, there is a tree level contribution. We find that chiral loop contributions might be important in both cases. The calculated amplitudes are sensitive on the coupling constant describing the interaction of positive and negative parity heavy meson multiplets with the light pseudoscalars. The counter-terms contributions are also present in the amplitudes D_{s1}(2460) --> Ds* \pi 0 and D*_{s0}(2317) --> Ds \pi 0. We explore experimentally known ratio of the decay widths for these two decay modes to estimate the size of counter-terms contributions. We determine decay widths for both decay modes to be Gamma (D_{s1}(2460) --> Ds \pi + \pi -) = 0.25 keV and Gamma (D_{s1}(2460) --> Ds + \pi 0 \pi 0 ) = 0.15 keV.
|
2206.13874
|
B. S. Ratanpal
|
B. S. Ratanpal and Bhavesh Suthar
|
A new solution of Einstein's field equations in isotropic coordinates
|
17 pages,6 figures
| null | null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this work, an exact solution of Einstein's field equations in isotropic
coordinates for anisotropic matter distribution is obtained by considering a
particular metric choice of metric potential $g_{rr}$. To check the feasibility
of the model, we have investigated all the physical characteristics of a
realistic star. It is found that the model is potentially stable, and the
adiabatic index is greater than $\frac{4}{3}$. The model have been analysed for
Compact star \textbf{4U 1538-52}.
|
[
{
"created": "Tue, 28 Jun 2022 10:24:17 GMT",
"version": "v1"
}
] |
2022-06-29
|
[
[
"Ratanpal",
"B. S.",
""
],
[
"Suthar",
"Bhavesh",
""
]
] |
In this work, an exact solution of Einstein's field equations in isotropic coordinates for anisotropic matter distribution is obtained by considering a particular metric choice of metric potential $g_{rr}$. To check the feasibility of the model, we have investigated all the physical characteristics of a realistic star. It is found that the model is potentially stable, and the adiabatic index is greater than $\frac{4}{3}$. The model have been analysed for Compact star \textbf{4U 1538-52}.
|
2405.03241
|
Zafri Ahmed Borboruah
|
Zafri A. Borboruah, Anish Ghoshal, Seyda Ipek
|
Probing flavor violation and baryogenesis via primordial gravitational
waves
|
minor changes, results unchanged, matches published version
|
JHEP 07 (2024) 228
|
10.1007/JHEP07(2024)228
| null |
hep-ph astro-ph.CO gr-qc
|
http://creativecommons.org/licenses/by/4.0/
|
We show that observations of primordial gravitational waves of inflationary
origin can shed light into the scale of flavor violation in a flavon model
which also explains the mass hierarchy of fermions. The energy density stored
in oscillations of the flavon field around the minimum of its potential
redshifts as matter and is expected to dominate over radiation in the early
universe. At the same time, the evolution of primordial gravitational waves
acts as bookkeeping to understand the expansion history of the universe.
Importantly, the gravitational wave spectrum is different if there is an early
flavon dominated era compared to radiation domination expected from a standard
cosmological model and this spectrum gets damped by the entropy released in
flavon decays, determined by the mass of the flavon field $m_S$ and new scale
of flavor violation $\Lambda_{\rm FV}$. We derive analytical expressions of the
frequency above which the spectrum is damped, as-well-as the amount of damping,
in terms of $m_S$ and $\Lambda_{\rm FV}$. We show that the damping of the
gravitational wave spectrum would be detectable at BBO, DECIGO, U-DECIGO,
$\mu-$ARES, LISA, CE and ET detectors for $\Lambda_{\rm FV}=10^{5-10}$ GeV and
$m_S=\mathcal{O({\rm TeV})}$. Furthermore, the flavon decays can source the
baryon asymmetry of the universe. We identify the $m_S-\Lambda_{\rm FV}$
parameter space where the observed baryon asymmetry $\eta \sim 10^{-10}$ is
produced and can be tested by gravitational wave detectors like LISA and ET. We
also discuss our results in the context of the recently measured stochastic
gravitational background signals by NANOGrav.
|
[
{
"created": "Mon, 6 May 2024 07:50:29 GMT",
"version": "v1"
},
{
"created": "Thu, 25 Jul 2024 07:54:24 GMT",
"version": "v2"
}
] |
2024-07-26
|
[
[
"Borboruah",
"Zafri A.",
""
],
[
"Ghoshal",
"Anish",
""
],
[
"Ipek",
"Seyda",
""
]
] |
We show that observations of primordial gravitational waves of inflationary origin can shed light into the scale of flavor violation in a flavon model which also explains the mass hierarchy of fermions. The energy density stored in oscillations of the flavon field around the minimum of its potential redshifts as matter and is expected to dominate over radiation in the early universe. At the same time, the evolution of primordial gravitational waves acts as bookkeeping to understand the expansion history of the universe. Importantly, the gravitational wave spectrum is different if there is an early flavon dominated era compared to radiation domination expected from a standard cosmological model and this spectrum gets damped by the entropy released in flavon decays, determined by the mass of the flavon field $m_S$ and new scale of flavor violation $\Lambda_{\rm FV}$. We derive analytical expressions of the frequency above which the spectrum is damped, as-well-as the amount of damping, in terms of $m_S$ and $\Lambda_{\rm FV}$. We show that the damping of the gravitational wave spectrum would be detectable at BBO, DECIGO, U-DECIGO, $\mu-$ARES, LISA, CE and ET detectors for $\Lambda_{\rm FV}=10^{5-10}$ GeV and $m_S=\mathcal{O({\rm TeV})}$. Furthermore, the flavon decays can source the baryon asymmetry of the universe. We identify the $m_S-\Lambda_{\rm FV}$ parameter space where the observed baryon asymmetry $\eta \sim 10^{-10}$ is produced and can be tested by gravitational wave detectors like LISA and ET. We also discuss our results in the context of the recently measured stochastic gravitational background signals by NANOGrav.
|
hep-ph/9502378
|
Sekretariat Phil. weg16
|
Berthold Stech
|
Form Factor Relations for Heavy-to-Light Transitions
|
12 pages, Latex; Relativistic covariant form, results unchanged,
references added, to be published in Physics Lett. B
|
Phys.Lett.B354:447-452,1995
|
10.1016/0370-2693(95)00661-4
|
HD-THEP-95-4 (revised)
|
hep-ph
| null |
Assuming simple properties of the spectator particle in weak decays the form
factors of hadronic current matrix elements are shown to be related to a single
universal function. The Isgur-Wise result for heavy-to-heavy transitions
follows as well as similar relations for heavy-to-light decay processes. The
approximation should hold for total energies of the final particle large
compared to the confinement scale. A comparison with experimentally determined
D-decay form factors and QCD sum rule results for B-decays is very encouraging.
|
[
{
"created": "Thu, 23 Feb 1995 11:05:26 GMT",
"version": "v1"
},
{
"created": "Thu, 22 Jun 1995 10:33:24 GMT",
"version": "v2"
}
] |
2010-11-01
|
[
[
"Stech",
"Berthold",
""
]
] |
Assuming simple properties of the spectator particle in weak decays the form factors of hadronic current matrix elements are shown to be related to a single universal function. The Isgur-Wise result for heavy-to-heavy transitions follows as well as similar relations for heavy-to-light decay processes. The approximation should hold for total energies of the final particle large compared to the confinement scale. A comparison with experimentally determined D-decay form factors and QCD sum rule results for B-decays is very encouraging.
|
2209.05064
|
Deog Ki Hong
|
Deog Ki Hong, Gyurin Kim, Jun Beom Park
|
Unitarity and Dilaton effective theory
|
10 pages, 4 figures
| null |
10.1007/s40042-022-00629-1
|
PNUTP-22/A05
|
hep-ph hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
From the low-energy effective theory of dilatons, consistent with the scale
anomaly, we calculate the $2\to2$ scattering amplitudes of dilatons. We find
that the one-loop amplitude violates the unitarity bound as the scattering
energy approaches the cutoff of the effective theory, $\sqrt{s}=\sqrt{4\pi}
f_D$. We then show that the inclusion of the next-to-lightest state, namely the
spin-2 state, of mass around the cutoff improves the unitarity. The unitarity
argument suggests that the mass ratio of the dilaton and the spin-2 state is
proportional to the square of the Miransky-BKT scaling of the near conformal
dynamics.
|
[
{
"created": "Mon, 12 Sep 2022 07:51:16 GMT",
"version": "v1"
}
] |
2022-10-26
|
[
[
"Hong",
"Deog Ki",
""
],
[
"Kim",
"Gyurin",
""
],
[
"Park",
"Jun Beom",
""
]
] |
From the low-energy effective theory of dilatons, consistent with the scale anomaly, we calculate the $2\to2$ scattering amplitudes of dilatons. We find that the one-loop amplitude violates the unitarity bound as the scattering energy approaches the cutoff of the effective theory, $\sqrt{s}=\sqrt{4\pi} f_D$. We then show that the inclusion of the next-to-lightest state, namely the spin-2 state, of mass around the cutoff improves the unitarity. The unitarity argument suggests that the mass ratio of the dilaton and the spin-2 state is proportional to the square of the Miransky-BKT scaling of the near conformal dynamics.
|
hep-ph/0204089
|
Vladimir Galkin
|
D. Ebert, R. N. Faustov, V. O. Galkin
|
Radiative M1-decays of heavy-light mesons in the relativistic quark
model
|
11 pages, 2 figures, few comments added, version to appear in Phys.
Lett. B
|
Phys.Lett. B537 (2002) 241-248
|
10.1016/S0370-2693(02)01939-1
|
HU-EP-02/14
|
hep-ph hep-ex
| null |
Radiative magnetic dipole decays of heavy-light vector mesons into
pseudoscalar mesons V -> P\gamma are considered within the relativistic quark
model. The light quark is treated completely relativistically, while for the
heavy quark the 1/m_Q expansion is used. It is found that relativistic effects
result in a significant reduction of decay rates. Comparison with previous
predictions and recent experimental data is presented.
|
[
{
"created": "Mon, 8 Apr 2002 14:13:56 GMT",
"version": "v1"
},
{
"created": "Fri, 10 May 2002 16:13:24 GMT",
"version": "v2"
}
] |
2009-11-07
|
[
[
"Ebert",
"D.",
""
],
[
"Faustov",
"R. N.",
""
],
[
"Galkin",
"V. O.",
""
]
] |
Radiative magnetic dipole decays of heavy-light vector mesons into pseudoscalar mesons V -> P\gamma are considered within the relativistic quark model. The light quark is treated completely relativistically, while for the heavy quark the 1/m_Q expansion is used. It is found that relativistic effects result in a significant reduction of decay rates. Comparison with previous predictions and recent experimental data is presented.
|
1401.3310
|
Ikaros Bigi
|
I. Bediaga, I.I. Bigi, J. Miranda, A. Reis
|
CP Asymmetries in Three-Body Final States in Charged $D$ Decays & CPT
Invariance
|
14 pages, 6 Figures
|
Phys. Rev. D 89, 074024 (2014)
|
10.1103/PhysRevD.89.074024
|
UND-HEP-14-BIG01
|
hep-ph hep-ex
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The study of local \cp \ asymmetry in Dalitz plots of charm (& beauty) decays
gives us more information about the underlying dynamics than the ratio between
total rates. In this paper we explore the consequences of the constraint from
\cpt \ symmetry with emphasis on three-body $D$ decays. We show simulations of
$D^{\pm} \to \pi^{\pm}K^+K^-$ and discuss correlations with measured $D^{\pm}
\to \pi^{\pm}\pi^+ \pi^-$. There are important comments about analysies of
recent LHCb data in \cp\ asymmetries for $B^{\pm}$ decays to three-body final
states.
|
[
{
"created": "Tue, 14 Jan 2014 19:56:38 GMT",
"version": "v1"
},
{
"created": "Fri, 7 Feb 2014 14:36:17 GMT",
"version": "v2"
},
{
"created": "Wed, 12 Mar 2014 19:36:19 GMT",
"version": "v3"
}
] |
2014-04-23
|
[
[
"Bediaga",
"I.",
""
],
[
"Bigi",
"I. I.",
""
],
[
"Miranda",
"J.",
""
],
[
"Reis",
"A.",
""
]
] |
The study of local \cp \ asymmetry in Dalitz plots of charm (& beauty) decays gives us more information about the underlying dynamics than the ratio between total rates. In this paper we explore the consequences of the constraint from \cpt \ symmetry with emphasis on three-body $D$ decays. We show simulations of $D^{\pm} \to \pi^{\pm}K^+K^-$ and discuss correlations with measured $D^{\pm} \to \pi^{\pm}\pi^+ \pi^-$. There are important comments about analysies of recent LHCb data in \cp\ asymmetries for $B^{\pm}$ decays to three-body final states.
|
1611.05330
|
Andreas Schmitt
|
Florian Preis, Andreas Schmitt
|
Phases of dense matter with holographic instantons
|
9 pages, contribution to the proceedings of "XIIth Quark Confinement
and the Hadron Spectrum" in Thessaloniki, Greece, Aug 28 - Sep 4, 2016
| null |
10.1051/epjconf/201713709009
| null |
hep-ph hep-th nucl-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We discuss nuclear matter and the transition to quark matter in the
decompactified limit of the Sakai-Sugimoto model. Nuclear matter is included
through instantons on the flavor branes of the model. Our approximation is
based on the flat-space solution, but we allow for a dynamical instanton width
and deformation and compute the energetically preferred number of instanton
layers in the bulk as a function of the baryon chemical potential. We determine
the regions in parameter space where the binding energy of nuclear matter is
like in QCD, and compute the phase diagram in the plane of temperature and
chemical potential.
|
[
{
"created": "Wed, 16 Nov 2016 15:47:36 GMT",
"version": "v1"
}
] |
2017-04-05
|
[
[
"Preis",
"Florian",
""
],
[
"Schmitt",
"Andreas",
""
]
] |
We discuss nuclear matter and the transition to quark matter in the decompactified limit of the Sakai-Sugimoto model. Nuclear matter is included through instantons on the flavor branes of the model. Our approximation is based on the flat-space solution, but we allow for a dynamical instanton width and deformation and compute the energetically preferred number of instanton layers in the bulk as a function of the baryon chemical potential. We determine the regions in parameter space where the binding energy of nuclear matter is like in QCD, and compute the phase diagram in the plane of temperature and chemical potential.
|
gr-qc/9409024
|
Ernie Chow
|
Anthony W.C.Lun and Ernest W.M.Chow
|
The Role of the Apparent Horizon in the Evolution of Robinson-Trautman
%%EINSTEIN-Maxwell Spacetimes
|
14 pages, report MU-DM-App-94/16
| null | null | null |
gr-qc
| null |
The `runaway solutions' of the Lorentz-Dirac equation of a charged particle
interacting with its own field in classical electrodynamics are well-known.
This type of self accelerated phenomena also exists in the solutions of the
Einstein-Maxwell equations in general relativity. In particular, runaway
solutions occur in a class of simple models known as the `Asymptotically Flat
Robinson-Trautman Einstein-Maxwell' (AFRTEM) spacetimes. Consequently these
spacetimes cannot evolve to their unique regular steady state, viz. a charged
non-rotating black hole. This seems to contradict the established results that
charged non-rotating black holes are stable under first order perturbations. We
show that if an AFRTEM spacetime also possesses an apparent horizon, then it
has a Lyapunov functional. This suggests that the evolution equations with
additional constraints arising from the apparent horizon would evolve stably to
a charged non-rotating black hole. We also demonstrate that the linearised
equations of these restricted spacetimes are stable and the exponentially
growing dipole modes, which give rise to self accelerated motions in classical
electrodynamics are also eliminated.
|
[
{
"created": "Tue, 13 Sep 1994 10:53:01 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Lun",
"Anthony W. C.",
""
],
[
"Chow",
"Ernest W. M.",
""
]
] |
The `runaway solutions' of the Lorentz-Dirac equation of a charged particle interacting with its own field in classical electrodynamics are well-known. This type of self accelerated phenomena also exists in the solutions of the Einstein-Maxwell equations in general relativity. In particular, runaway solutions occur in a class of simple models known as the `Asymptotically Flat Robinson-Trautman Einstein-Maxwell' (AFRTEM) spacetimes. Consequently these spacetimes cannot evolve to their unique regular steady state, viz. a charged non-rotating black hole. This seems to contradict the established results that charged non-rotating black holes are stable under first order perturbations. We show that if an AFRTEM spacetime also possesses an apparent horizon, then it has a Lyapunov functional. This suggests that the evolution equations with additional constraints arising from the apparent horizon would evolve stably to a charged non-rotating black hole. We also demonstrate that the linearised equations of these restricted spacetimes are stable and the exponentially growing dipole modes, which give rise to self accelerated motions in classical electrodynamics are also eliminated.
|
1106.1204
|
Krzysztof M. Graczyk
|
Krzysztof M. Graczyk
|
Two-Photon Exchange Effect Studied with Neural Networks
|
9 pages, 4 figures, the manuscript is divided into 4 sections, 5
appendixes are added, the text is enriched by the more detailed description
of the Bayesian formalism, one new figure is also added
| null |
10.1103/PhysRevC.84.034314
| null |
hep-ph nucl-ex nucl-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
An approach to the extraction of the two-photon exchange (TPE) correction
from elastic $ep$ scattering data is presented. The cross section, polarization
transfer (PT), and charge asymmetry data are considered. It is assumed that the
TPE correction to the PT data is negligible. The form factors and TPE
correcting term are given by one multidimensional function approximated by the
feed forward neural network (NN). To find a model-independent approximation the
Bayesian framework for the NNs is adapted. A large number of different
parametrizations is considered. The most optimal model is indicated by the
Bayesian algorithm. The obtained fit of the TPE correction behaves linearly in
epsilon but it has a nontrivial Q2 dependence. A strong dependence of the TPE
fit on the choice of parametrization is observed.
|
[
{
"created": "Mon, 6 Jun 2011 21:54:57 GMT",
"version": "v1"
},
{
"created": "Tue, 30 Aug 2011 18:20:33 GMT",
"version": "v2"
}
] |
2015-05-28
|
[
[
"Graczyk",
"Krzysztof M.",
""
]
] |
An approach to the extraction of the two-photon exchange (TPE) correction from elastic $ep$ scattering data is presented. The cross section, polarization transfer (PT), and charge asymmetry data are considered. It is assumed that the TPE correction to the PT data is negligible. The form factors and TPE correcting term are given by one multidimensional function approximated by the feed forward neural network (NN). To find a model-independent approximation the Bayesian framework for the NNs is adapted. A large number of different parametrizations is considered. The most optimal model is indicated by the Bayesian algorithm. The obtained fit of the TPE correction behaves linearly in epsilon but it has a nontrivial Q2 dependence. A strong dependence of the TPE fit on the choice of parametrization is observed.
|
gr-qc/0610015
|
Martin Tajmar
|
M. Tajmar, F. Plesescu, B. Seifert, K. Marhold
|
Measurement of Gravitomagnetic and Acceleration Fields Around Rotating
Superconductors
|
To appear in the proceedings of the STAIF-2007 conference published
by AIP
|
AIP Conf.Proc.880:1071-1082,2007
|
10.1063/1.2437552
| null |
gr-qc
| null |
It is well known that a rotating superconductor produces a magnetic field
proportional to its angular velocity. The authors conjectured earlier, that in
addition to this so-called London moment, also a large gravitomagnetic field
should appear to explain an apparent mass increase of Niobium Cooper-pairs. A
similar field is predicted from Einstein's general relativity theory and the
presently observed amount of dark energy in the universe. An experimental
facility was designed and built to measure small acceleration fields as well as
gravitomagnetic fields in the vicinity of a fast rotating and accelerating
superconductor in order to detect this so-called gravitomagnetic London moment.
This paper summarizes the efforts and results that have been obtained so far.
Measurements with Niobium superconductors indeed show first signs which appear
to be within a factor of 2 of our theoretical prediction. Possible error
sources as well as the experimental difficulties are reviewed and discussed. If
the gravitomagnetic London moment indeed exists, acceleration fields could be
produced in a laboratory environment.
|
[
{
"created": "Wed, 4 Oct 2006 18:44:09 GMT",
"version": "v1"
},
{
"created": "Thu, 5 Oct 2006 07:24:13 GMT",
"version": "v2"
},
{
"created": "Tue, 17 Oct 2006 16:06:22 GMT",
"version": "v3"
}
] |
2010-11-11
|
[
[
"Tajmar",
"M.",
""
],
[
"Plesescu",
"F.",
""
],
[
"Seifert",
"B.",
""
],
[
"Marhold",
"K.",
""
]
] |
It is well known that a rotating superconductor produces a magnetic field proportional to its angular velocity. The authors conjectured earlier, that in addition to this so-called London moment, also a large gravitomagnetic field should appear to explain an apparent mass increase of Niobium Cooper-pairs. A similar field is predicted from Einstein's general relativity theory and the presently observed amount of dark energy in the universe. An experimental facility was designed and built to measure small acceleration fields as well as gravitomagnetic fields in the vicinity of a fast rotating and accelerating superconductor in order to detect this so-called gravitomagnetic London moment. This paper summarizes the efforts and results that have been obtained so far. Measurements with Niobium superconductors indeed show first signs which appear to be within a factor of 2 of our theoretical prediction. Possible error sources as well as the experimental difficulties are reviewed and discussed. If the gravitomagnetic London moment indeed exists, acceleration fields could be produced in a laboratory environment.
|
2304.10299
|
Paul D. Grannis
|
J.A. Bagger, S. Belomestnykh, P.C. Bhat, J.E. Brau, M. Demarteau, D.
Denisov, S. Gori, P.D. Grannis, T. Junginger, A.J. Lankford, M. Liepe, T.W.
Markiewicz, H.E. Montgomery, M. Perelstein, M.E. Peskin, J. Strube, A.P.
White, G.W. Wilson
|
Statement from the American Linear Collider Committee to the P5 subpanel
|
6 pages
| null | null | null |
hep-ph hep-ex
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
This statement from the American Linear Collider Committee to the P5 subpanel
has three purposes. It presents a brief summary of the case for an $e^+e^-$
Higgs factory that has emerged from Snowmass 2021. It highlights the special
virtues of the ILC that are shared with other linear colliders but not with
circular colliders. Finally, it calls attention to the resources available in
the ILC White Paper for Snowmass (arXiv:2203.07622). The ALCC urges P5 to move
the Higgs factory forward as a global project by assigning the idea of an
$e^+e^-$ Higgs factory high priority, initiating a global discussion of the
technology choice and cost sharing, and offering the option of siting the Higgs
factory in the U.S.
|
[
{
"created": "Thu, 20 Apr 2023 13:28:20 GMT",
"version": "v1"
},
{
"created": "Wed, 26 Apr 2023 14:07:45 GMT",
"version": "v2"
},
{
"created": "Wed, 17 May 2023 15:03:21 GMT",
"version": "v3"
}
] |
2023-05-18
|
[
[
"Bagger",
"J. A.",
""
],
[
"Belomestnykh",
"S.",
""
],
[
"Bhat",
"P. C.",
""
],
[
"Brau",
"J. E.",
""
],
[
"Demarteau",
"M.",
""
],
[
"Denisov",
"D.",
""
],
[
"Gori",
"S.",
""
],
[
"Grannis",
"P. D.",
""
],
[
"Junginger",
"T.",
""
],
[
"Lankford",
"A. J.",
""
],
[
"Liepe",
"M.",
""
],
[
"Markiewicz",
"T. W.",
""
],
[
"Montgomery",
"H. E.",
""
],
[
"Perelstein",
"M.",
""
],
[
"Peskin",
"M. E.",
""
],
[
"Strube",
"J.",
""
],
[
"White",
"A. P.",
""
],
[
"Wilson",
"G. W.",
""
]
] |
This statement from the American Linear Collider Committee to the P5 subpanel has three purposes. It presents a brief summary of the case for an $e^+e^-$ Higgs factory that has emerged from Snowmass 2021. It highlights the special virtues of the ILC that are shared with other linear colliders but not with circular colliders. Finally, it calls attention to the resources available in the ILC White Paper for Snowmass (arXiv:2203.07622). The ALCC urges P5 to move the Higgs factory forward as a global project by assigning the idea of an $e^+e^-$ Higgs factory high priority, initiating a global discussion of the technology choice and cost sharing, and offering the option of siting the Higgs factory in the U.S.
|
1512.04850
|
Keisuke Harigaya
|
Keisuke Harigaya and Yasunori Nomura
|
Composite Models for the 750 GeV Diphoton Excess
|
7 pages, 1 figure; matches the published version
| null |
10.1016/j.physletb.2016.01.026
|
UCB-PTH-15/15
|
hep-ph hep-ex
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We present composite models explaining the diphoton excess of mass around 750
GeV recently reported by the LHC experiments.
|
[
{
"created": "Tue, 15 Dec 2015 16:47:58 GMT",
"version": "v1"
},
{
"created": "Wed, 16 Dec 2015 08:19:11 GMT",
"version": "v2"
},
{
"created": "Thu, 12 May 2016 04:17:57 GMT",
"version": "v3"
}
] |
2016-05-13
|
[
[
"Harigaya",
"Keisuke",
""
],
[
"Nomura",
"Yasunori",
""
]
] |
We present composite models explaining the diphoton excess of mass around 750 GeV recently reported by the LHC experiments.
|
1608.00577
|
Moritz Platscher
|
Manfred Lindner, Alexander Merle, Moritz Platscher and Carlos E.
Yaguna
|
Fermionic WIMPs and Vacuum Stability in the Scotogenic Model
|
8 pages, 6 figures; content matches published version
|
Phys. Rev. D 94, 115027 (2016)
|
10.1103/PhysRevD.94.115027
|
MPP-2016-168
|
hep-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We demonstrate that the condition of vacuum stability severely restricts
scenarios with fermionic WIMP dark matter in the scotogenic model. The sizable
Yukawa couplings that are required to satisfy the dark matter constraint via
thermal freeze-out in these scenarios tend to destabilise the vacuum at scales
below that of the heaviest singlet fermion, rendering the model inconsistent
from a theoretical point of view. By means of a scan over the parameter space,
we study the impact of these renormalisation group effects on the viable
regions of this model. Our analysis shows that a fraction of more than 90% of
the points compatible with all known experimental constraints - including
neutrino masses, the dark matter density, and lepton flavour violation - is
actually inconsistent.
|
[
{
"created": "Mon, 1 Aug 2016 20:00:02 GMT",
"version": "v1"
},
{
"created": "Wed, 14 Dec 2016 11:22:21 GMT",
"version": "v2"
}
] |
2017-01-04
|
[
[
"Lindner",
"Manfred",
""
],
[
"Merle",
"Alexander",
""
],
[
"Platscher",
"Moritz",
""
],
[
"Yaguna",
"Carlos E.",
""
]
] |
We demonstrate that the condition of vacuum stability severely restricts scenarios with fermionic WIMP dark matter in the scotogenic model. The sizable Yukawa couplings that are required to satisfy the dark matter constraint via thermal freeze-out in these scenarios tend to destabilise the vacuum at scales below that of the heaviest singlet fermion, rendering the model inconsistent from a theoretical point of view. By means of a scan over the parameter space, we study the impact of these renormalisation group effects on the viable regions of this model. Our analysis shows that a fraction of more than 90% of the points compatible with all known experimental constraints - including neutrino masses, the dark matter density, and lepton flavour violation - is actually inconsistent.
|
0811.1206
|
Brian Hannafious
|
Brian Hannafious, Matthias Burkardt
|
The Boer-Mulders Function: Models and Universality
|
6 pages, 1 figure, talk at the "LIGHT CONE 2008: Relativistic Nuclear
and Particle Physics" conference, Mulhouse, France, July 7-11, 2008
|
PoS LC2008:032,2008
| null | null |
hep-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The sign of the Boer-Mulders function $h_1^\perp$ is related to the sign of
the GPD $\bar{E}_T$ through the mechanism of chromodynamic lensing. Model
calculations of the sign of $\bar{E}_T$ indicate that the sign of $h_1^\perp$
may be the same in all ground state hadrons.
|
[
{
"created": "Fri, 7 Nov 2008 20:11:44 GMT",
"version": "v1"
}
] |
2009-02-19
|
[
[
"Hannafious",
"Brian",
""
],
[
"Burkardt",
"Matthias",
""
]
] |
The sign of the Boer-Mulders function $h_1^\perp$ is related to the sign of the GPD $\bar{E}_T$ through the mechanism of chromodynamic lensing. Model calculations of the sign of $\bar{E}_T$ indicate that the sign of $h_1^\perp$ may be the same in all ground state hadrons.
|
1710.05190
|
Pat Scott
|
Pat Scott
|
Neutrino telescope searches for dark matter in the Sun
|
7 pages, 4 figures, to appear in the Proceedings of Rencontres du
Vietnam: Exploring the Dark Universe, Quy Nhon, Vietnam, July 23-28
| null | null | null |
hep-ph astro-ph.CO
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
I give a brief review of a few recent developments and future directions in
the search for dark matter using high-energy neutrinos from the Sun. This
includes the ability to recast neutrino telescope limits on nuclear scattering
of dark matter to arbitrary new theories, and new calculations of the solar
atmospheric background relevant to such searches. I also touch on applications
to global searches for new physics, and prospects for improving searches for
asymmetric dark matter in the Sun.
|
[
{
"created": "Sat, 14 Oct 2017 14:11:15 GMT",
"version": "v1"
}
] |
2017-10-17
|
[
[
"Scott",
"Pat",
""
]
] |
I give a brief review of a few recent developments and future directions in the search for dark matter using high-energy neutrinos from the Sun. This includes the ability to recast neutrino telescope limits on nuclear scattering of dark matter to arbitrary new theories, and new calculations of the solar atmospheric background relevant to such searches. I also touch on applications to global searches for new physics, and prospects for improving searches for asymmetric dark matter in the Sun.
|
gr-qc/0101030
|
Lorenzo Iorio
|
Lorenzo Iorio and Erricos C. Pavlis
|
Tidal satellite perturbations and the Lense-Thirring effect
|
6 pages, LaTex, to appear in Journal of the Geodetic Society of
Japan, vol. 47, no. 1, special issue for the Proceedings of The XIV
International Symposium on Earth tides (ETS 2000) held at Mizusawa, Iwate,
Japan from August 28 to September 1, 2000
|
J.Geodet.Soc.Jap.47:1-7,2001
|
10.11366/sokuchi1954.47.169
| null |
gr-qc astro-ph physics.geo-ph physics.space-ph
| null |
The tiny general relativistic Lense-Thirring effect can be measured by means
of a suitable combination of the orbital residuals of the nodes of LAGEOS and
LAGEOS II and the perigee of LAGEOS II. This observable is affected, among
other factors, by the Earth' s solid and ocean tides. They induce long-period
orbital perturbations that, over observational periods of few years, may alias
the detection of the gravitomagnetic secular trend of interest. In this paper
we calculate explicitly the most relevant tidal perturbations acting upon
LAGEOSs and assess their influence on the detection of the Lense-Thirring
effect. The present day level of knowledge of the solid and ocean tides allow
us to conclude that their influence on it ranges from almost 4% over 4 years to
less than 2% over 7 years.
|
[
{
"created": "Tue, 9 Jan 2001 09:39:35 GMT",
"version": "v1"
}
] |
2013-11-12
|
[
[
"Iorio",
"Lorenzo",
""
],
[
"Pavlis",
"Erricos C.",
""
]
] |
The tiny general relativistic Lense-Thirring effect can be measured by means of a suitable combination of the orbital residuals of the nodes of LAGEOS and LAGEOS II and the perigee of LAGEOS II. This observable is affected, among other factors, by the Earth' s solid and ocean tides. They induce long-period orbital perturbations that, over observational periods of few years, may alias the detection of the gravitomagnetic secular trend of interest. In this paper we calculate explicitly the most relevant tidal perturbations acting upon LAGEOSs and assess their influence on the detection of the Lense-Thirring effect. The present day level of knowledge of the solid and ocean tides allow us to conclude that their influence on it ranges from almost 4% over 4 years to less than 2% over 7 years.
|
2204.07599
|
Jainendra Kumar Singh Dr.
|
J. K. Singh, Akanksha Singh, G. K. Goswami and J. Jena
|
Dynamics of a parametrized dark energy model in $f(R,T)$ gravity
|
15 pages, 20 figures
|
Annals of Physics 443 (2022) 168958
|
10.1016/j.aop.2022.168958
| null |
gr-qc
|
http://creativecommons.org/licenses/by/4.0/
|
We investigate a flat FLRW-model in $f(R,T)$-gravity, which includes the
quadratic variation in scalar curvature $R$ and the linear term of the trace of
the stress-energy tensor $T$. In turn, we establish the model has the behaviour
of the late time Universe, which is accelerated expanding and ends up in a big
rip. Using the parametrization of scale factor $a(t)$, we propose a model,
which begins with point-type singularity, i.e., the model starts with a point
of zero volume, infinite energy density and infinite temperature. The model's
behaviour is accelerated expanding at present and $\Lambda$CDM in late times.
Finally, the proposed model behaves like a quintessence dark energy model in
the present time and is consistent with standard cosmology $\Lambda$CDM in late
times.
|
[
{
"created": "Fri, 15 Apr 2022 18:02:05 GMT",
"version": "v1"
},
{
"created": "Fri, 6 May 2022 06:22:50 GMT",
"version": "v2"
},
{
"created": "Tue, 9 Aug 2022 08:00:58 GMT",
"version": "v3"
}
] |
2022-08-10
|
[
[
"Singh",
"J. K.",
""
],
[
"Singh",
"Akanksha",
""
],
[
"Goswami",
"G. K.",
""
],
[
"Jena",
"J.",
""
]
] |
We investigate a flat FLRW-model in $f(R,T)$-gravity, which includes the quadratic variation in scalar curvature $R$ and the linear term of the trace of the stress-energy tensor $T$. In turn, we establish the model has the behaviour of the late time Universe, which is accelerated expanding and ends up in a big rip. Using the parametrization of scale factor $a(t)$, we propose a model, which begins with point-type singularity, i.e., the model starts with a point of zero volume, infinite energy density and infinite temperature. The model's behaviour is accelerated expanding at present and $\Lambda$CDM in late times. Finally, the proposed model behaves like a quintessence dark energy model in the present time and is consistent with standard cosmology $\Lambda$CDM in late times.
|
hep-ph/9512379
| null |
M. Anselmino, M. Boglione (University and INFN, Torino), J. Hansson
(Lulea University) and F. Murgia (INFN, Cagliari)
|
Polarized inclusive leptoproduction, $\ell N \to hX$, and the hadron
helicity density matrix, $\rho(h)$: possible measurements and predictions
|
17 pages + 4 figures, plain LATeX, figures appended as uuencoded,
compressed postscript file
|
Phys.Rev. D54 (1996) 828-837
|
10.1103/PhysRevD.54.828
|
DFTT 61/95, INFNCA-TH9526
|
hep-ph
| null |
We discuss the production of hadrons in polarized lepton nucleon interactions
and in the current jet fragmentation region; using the QCD hard scattering
formalism we compute the helicity density matrix of the hadron and show how its
elements, when measurable, can give information on the spin structure of the
nucleon and the spin dependence of the quark fragmentation process. The cases
of $\rho$ vector mesons and $\Lambda$ baryons are considered in more details
and, within simplifying assumptions, some estimates are given.
|
[
{
"created": "Wed, 20 Dec 1995 16:29:33 GMT",
"version": "v1"
}
] |
2009-10-28
|
[
[
"Anselmino",
"M.",
"",
"University and INFN, Torino"
],
[
"Boglione",
"M.",
"",
"University and INFN, Torino"
],
[
"Hansson",
"J.",
"",
"Lulea University"
],
[
"Murgia",
"F.",
"",
"INFN, Cagliari"
]
] |
We discuss the production of hadrons in polarized lepton nucleon interactions and in the current jet fragmentation region; using the QCD hard scattering formalism we compute the helicity density matrix of the hadron and show how its elements, when measurable, can give information on the spin structure of the nucleon and the spin dependence of the quark fragmentation process. The cases of $\rho$ vector mesons and $\Lambda$ baryons are considered in more details and, within simplifying assumptions, some estimates are given.
|
2003.06380
|
Adam Balcerzak
|
Adam Balcerzak, Konrad Marosek
|
Doubleverse entanglement in third quantized non-minimally coupled
varying constants cosmologies
|
9 pages, 4 figures
|
Eur. Phys. J. C 80, 709 (2020)
|
10.1140/epjc/s10052-020-8305-z
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper we consider a third quantized cosmological model with varying
speed of light $c$ and varying gravitational constant $G$ both represented by
non-minimally coupled scalar fields. The third quantization of such a model
leads to a scenario of the doubleverse with the two components being quantum
mechanically entangled. We calculate the two parameters describing the
entanglement, namely: the energy and the entropy of entanglement where the
latter appears to be a proper measure of the entanglement. We consider a
possibility that the entanglement can manifests itself as an effective perfect
fluid characterized by the time dependent barotropic index $w_{eff}$, which for
some specific case corresponds to the fluid of cosmic strings. It seems that
such an entanglement induced effective perfect fluid may generate significant
backreaction effect at early times.
|
[
{
"created": "Fri, 13 Mar 2020 16:57:51 GMT",
"version": "v1"
},
{
"created": "Sun, 22 Mar 2020 09:42:20 GMT",
"version": "v2"
},
{
"created": "Fri, 7 Aug 2020 15:05:37 GMT",
"version": "v3"
}
] |
2020-08-10
|
[
[
"Balcerzak",
"Adam",
""
],
[
"Marosek",
"Konrad",
""
]
] |
In this paper we consider a third quantized cosmological model with varying speed of light $c$ and varying gravitational constant $G$ both represented by non-minimally coupled scalar fields. The third quantization of such a model leads to a scenario of the doubleverse with the two components being quantum mechanically entangled. We calculate the two parameters describing the entanglement, namely: the energy and the entropy of entanglement where the latter appears to be a proper measure of the entanglement. We consider a possibility that the entanglement can manifests itself as an effective perfect fluid characterized by the time dependent barotropic index $w_{eff}$, which for some specific case corresponds to the fluid of cosmic strings. It seems that such an entanglement induced effective perfect fluid may generate significant backreaction effect at early times.
|
1011.1538
|
Farook Rahaman
|
F. Rahaman, Peter K. F. Kuhfittig, K. Chakraborty, A. A. Usmani and
Saibal Ray
|
Galactic rotation curves inspired by a noncommutative-geometry
background
|
12 pages, 3 figures. Published in Gen.Rel.Grav. 44 (2012) 905-916
|
Gen.Rel.Grav. 44 (2012) 905-916
|
10.1007/s10714-011-1320-5
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
This paper discusses the observed at rotation curves of galaxies in the
context of noncommutative geometry. The energy density of such a geometry is
diffused throughout a region due to the uncertainty encoded in the coordinate
commutator. This intrinsic property appears to be sufficient for producing
stable circular orbits, as well as attractive gravity, without the need for
dark matter.
|
[
{
"created": "Sat, 6 Nov 2010 05:41:21 GMT",
"version": "v1"
},
{
"created": "Thu, 6 Sep 2012 18:10:22 GMT",
"version": "v2"
}
] |
2016-11-25
|
[
[
"Rahaman",
"F.",
""
],
[
"Kuhfittig",
"Peter K. F.",
""
],
[
"Chakraborty",
"K.",
""
],
[
"Usmani",
"A. A.",
""
],
[
"Ray",
"Saibal",
""
]
] |
This paper discusses the observed at rotation curves of galaxies in the context of noncommutative geometry. The energy density of such a geometry is diffused throughout a region due to the uncertainty encoded in the coordinate commutator. This intrinsic property appears to be sufficient for producing stable circular orbits, as well as attractive gravity, without the need for dark matter.
|
gr-qc/9409052
|
Steve Carlip
|
S. Carlip
|
The Statistical Mechanics of the (2+1)-Dimensional Black Hole
|
12 pages, UCD-94-32 and NI-94011
|
Phys.Rev.D51:632-637,1995
|
10.1103/PhysRevD.51.632
| null |
gr-qc hep-th
| null |
The presence of a horizon breaks the gauge invariance of (2+1)-dimensional
general relativity, leading to the appearance of new physical states at the
horizon. I show that the entropy of the (2+1)-dimensional black hole can be
obtained as the logarithm of the number of these microscopic states.
|
[
{
"created": "Mon, 26 Sep 1994 20:32:41 GMT",
"version": "v1"
}
] |
2010-04-28
|
[
[
"Carlip",
"S.",
""
]
] |
The presence of a horizon breaks the gauge invariance of (2+1)-dimensional general relativity, leading to the appearance of new physical states at the horizon. I show that the entropy of the (2+1)-dimensional black hole can be obtained as the logarithm of the number of these microscopic states.
|
gr-qc/0603010
|
Martin Rocek
|
Martin Rocek and Patrick van Nieuwenhuizen
|
Does Smoothing Matter?
|
8 pages [References updated, minor corrections]
| null | null |
YITP-SB-06-01,ITFA-2006-09
|
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We study how inhomogeneities modify large scale parameters in General
Relativity. For a particular model, we obtain exact results: we compare an
infinite string of extremal black holes to a corresponding smooth line with the
same mass and charge in five dimensions. We find that the effective energy
density does not differ significantly.
|
[
{
"created": "Mon, 6 Mar 2006 07:56:02 GMT",
"version": "v1"
},
{
"created": "Tue, 29 Mar 2011 21:31:13 GMT",
"version": "v2"
}
] |
2011-03-31
|
[
[
"Rocek",
"Martin",
""
],
[
"van Nieuwenhuizen",
"Patrick",
""
]
] |
We study how inhomogeneities modify large scale parameters in General Relativity. For a particular model, we obtain exact results: we compare an infinite string of extremal black holes to a corresponding smooth line with the same mass and charge in five dimensions. We find that the effective energy density does not differ significantly.
|
0908.3273
|
Einan Gardi
|
Einan Gardi, Lorenzo Magnea
|
Infrared singularities in QCD amplitudes
|
20 pages, 3 figures. To be published in the proceedings of 23rd Les
Rencontres de Physique de la Vallee d'Aoste, La Thuile, Aosta Valley, Italy,
1 - 7 March 2009
|
Nuovo Cim.C32N5-6:137-157,2009
|
10.1393/ncc/i2010-10528-x
|
Edinburgh 2009/09
|
hep-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We review recent progress in determining the infrared singularity structure
of on-shell scattering amplitudes in massless gauge theories. We present a
simple ansatz where soft singularities of any scattering amplitude of massless
partons, to any loop order, are written as a sum over colour dipoles, governed
by the cusp anomalous dimension. We explain how this formula was obtained, as
the simplest solution to a newly-derived set of equations constraining the
singularity structure to all orders. We emphasize the physical ideas underlying
this derivation: the factorization of soft and collinear modes, the special
properties of soft gluon interactions, and the notion of the cusp anomaly.
Finally, we briefly discuss potential multi-loop contributions going beyond the
sum-over-dipoles formula, which cannot be excluded at present.
|
[
{
"created": "Mon, 24 Aug 2009 12:28:51 GMT",
"version": "v1"
}
] |
2014-11-20
|
[
[
"Gardi",
"Einan",
""
],
[
"Magnea",
"Lorenzo",
""
]
] |
We review recent progress in determining the infrared singularity structure of on-shell scattering amplitudes in massless gauge theories. We present a simple ansatz where soft singularities of any scattering amplitude of massless partons, to any loop order, are written as a sum over colour dipoles, governed by the cusp anomalous dimension. We explain how this formula was obtained, as the simplest solution to a newly-derived set of equations constraining the singularity structure to all orders. We emphasize the physical ideas underlying this derivation: the factorization of soft and collinear modes, the special properties of soft gluon interactions, and the notion of the cusp anomaly. Finally, we briefly discuss potential multi-loop contributions going beyond the sum-over-dipoles formula, which cannot be excluded at present.
|
hep-ph/0209347
|
Vergados Ioannis
|
J.D. Vergados (Theoretical Physcs Division, University of Ioannina,
Ioannina, Greece and Department of Physics, University of Cyprus, Nicosia,
Cyprus)
|
Neutrinoless double beta decay from a modern perspective
|
Only the abstract and the table of contents has been submitted to the
lanl archives
|
Phys.Rept.361:1-56,2002
|
10.1016/S0370-1573(01)00068-0
| null |
hep-ph
| null |
Neutrinoless double beta decay is a very important process both from the
particle and nuclear physics point of view. From the elementary particle point
of view it pops up in almost every model. giving rise, among others, to the
following mechanisms: a) The traditional contributions like the light neutrino
mass mechanism . b) The exotic R-parity violating supersymmetric (SUSY)
contributions. Similar considerations apply to its sister lepton and muon
number violating muon to positron conversion. The observation of neutrinoless
double beta decay will signal that the neutrinos are massive Majorana
particles. For nuclear physics it is challenging, because: 1) The nuclei, which
can undergo double beta decay, have complicated structure. 2) The energetically
allowed transitions are suppressed. 3) One must cope with the short distance
behavior of the transition operators. Thus novel effects (decay of pions in
flight between nucleons etc) have to be considered. 4) One has to take into
account possible momentum dependent terms of the nucleon current. For light
neutrinos such modifications of the nucleon current reduce the nuclear matrix
elements by about 25 per cent. In the case of heavy neutrino the effect is much
larger and model dependent. With the above effects the nuclear matrix elements
for all interesting nuclei A = 76, 82, 96, 100, 116, 128, 130, 136 and 150 are
discussed. Some have been obtained in the shell model but most in QRPA. Thus we
have extracted new limits on the various lepton violating parameters. We find
an average neutrino mass of about 0.5eV and, for reasonable choices of the
parameters of SUSY models, we get a stringent limit on the R-parity violating
parameter less than 0.00068.
|
[
{
"created": "Sat, 28 Sep 2002 19:42:28 GMT",
"version": "v1"
}
] |
2008-11-26
|
[
[
"Vergados",
"J. D.",
"",
"Theoretical Physcs Division, University of Ioannina,\n Ioannina, Greece and Department of Physics, University of Cyprus, Nicosia,\n Cyprus"
]
] |
Neutrinoless double beta decay is a very important process both from the particle and nuclear physics point of view. From the elementary particle point of view it pops up in almost every model. giving rise, among others, to the following mechanisms: a) The traditional contributions like the light neutrino mass mechanism . b) The exotic R-parity violating supersymmetric (SUSY) contributions. Similar considerations apply to its sister lepton and muon number violating muon to positron conversion. The observation of neutrinoless double beta decay will signal that the neutrinos are massive Majorana particles. For nuclear physics it is challenging, because: 1) The nuclei, which can undergo double beta decay, have complicated structure. 2) The energetically allowed transitions are suppressed. 3) One must cope with the short distance behavior of the transition operators. Thus novel effects (decay of pions in flight between nucleons etc) have to be considered. 4) One has to take into account possible momentum dependent terms of the nucleon current. For light neutrinos such modifications of the nucleon current reduce the nuclear matrix elements by about 25 per cent. In the case of heavy neutrino the effect is much larger and model dependent. With the above effects the nuclear matrix elements for all interesting nuclei A = 76, 82, 96, 100, 116, 128, 130, 136 and 150 are discussed. Some have been obtained in the shell model but most in QRPA. Thus we have extracted new limits on the various lepton violating parameters. We find an average neutrino mass of about 0.5eV and, for reasonable choices of the parameters of SUSY models, we get a stringent limit on the R-parity violating parameter less than 0.00068.
|
1211.4716
|
Wolfgang Lucha
|
Wolfgang Lucha and Franz F. Schoberl
|
Exact Solutions of Bethe-Salpeter Equations with Instantaneous
Interactions
|
16 pages, 3 figures; v2: slightly augmented summary, matches version
in PRD
|
Phys. Rev. D 87, 016009 (2013)
|
10.1103/PhysRevD.87.016009
|
HEPHY-PUB 921/12
|
hep-ph hep-th nucl-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The Bethe-Salpeter approach allows for quantum-field-theoretic descriptions
of relativistic bound states; its inherent complexity, however, usually
prevents to find its exact solutions. Under suitable simplifying assumptions
about the systems discussed, we derive analytically some examples of rigorous
solutions to the instantaneous homogeneous Bethe-Salpeter equation by relating
tentative solutions to the interactions responsible for the formation of bound
states.
|
[
{
"created": "Tue, 20 Nov 2012 11:28:05 GMT",
"version": "v1"
},
{
"created": "Mon, 7 Jan 2013 12:14:27 GMT",
"version": "v2"
}
] |
2013-05-30
|
[
[
"Lucha",
"Wolfgang",
""
],
[
"Schoberl",
"Franz F.",
""
]
] |
The Bethe-Salpeter approach allows for quantum-field-theoretic descriptions of relativistic bound states; its inherent complexity, however, usually prevents to find its exact solutions. Under suitable simplifying assumptions about the systems discussed, we derive analytically some examples of rigorous solutions to the instantaneous homogeneous Bethe-Salpeter equation by relating tentative solutions to the interactions responsible for the formation of bound states.
|
0711.0028
|
Antonio Pich
|
Antonio Pich
|
Selected topics on tau physics
|
Invited talk at the XXXI International Conference of Theoretical
Physics, "Matter to the Deepest", Ustron, Poland, 5-11 September 2007
|
ActaPhys.Polon.B38:3449-3458,2007
| null |
FTUV/07-1031, IFIC/07-80
|
hep-ph hep-ex
| null |
The B Factories have generated a large amount of new results on the tau
lepton. The present status of some selected topics on tau physics is presented:
charged-current universality tests, bounds on lepton-flavour violation, the
determination of alpha_s from the inclusive tau hadronic width, and the
measurement of |V_{us}| through the Cabibbo-suppressed decays of the tau
lepton.
|
[
{
"created": "Wed, 31 Oct 2007 22:34:16 GMT",
"version": "v1"
}
] |
2008-11-26
|
[
[
"Pich",
"Antonio",
""
]
] |
The B Factories have generated a large amount of new results on the tau lepton. The present status of some selected topics on tau physics is presented: charged-current universality tests, bounds on lepton-flavour violation, the determination of alpha_s from the inclusive tau hadronic width, and the measurement of |V_{us}| through the Cabibbo-suppressed decays of the tau lepton.
|
1910.13432
|
Franziska Hagelstein
|
Gilberto Colangelo, Franziska Hagelstein, Martin Hoferichter, Laetitia
Laub, Peter Stoffer
|
Longitudinal short-distance constraints for the hadronic light-by-light
contribution to $(g-2)_\mu$ with large-$N_c$ Regge models
|
85 pages, 33 figures, 5 tables; journal version, includes reply to
arXiv:1911.05874
| null |
10.1007/JHEP03(2020)101
|
INT-PUB-19-051
|
hep-ph hep-ex hep-lat nucl-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
While the low-energy part of the hadronic light-by-light (HLbL) tensor can be
constrained from data using dispersion relations, for a full evaluation of its
contribution to the anomalous magnetic moment of the muon $(g-2)_\mu$ also
mixed- and high-energy regions need to be estimated. Both can be addressed
within the operator product expansion (OPE), either for configurations where
all photon virtualities become large or one of them remains finite. Imposing
such short-distance constraints (SDCs) on the HLbL tensor is thus a major
aspect of a model-independent approach towards HLbL scattering. Here, we focus
on longitudinal SDCs, which concern the amplitudes containing the
pseudoscalar-pole contributions from $\pi^0$, $\eta$, $\eta'$. Since these
conditions cannot be fulfilled by a finite number of pseudoscalar poles, we
consider a tower of excited pseudoscalars, constraining their masses and
transition form factors from Regge theory, the OPE, and phenomenology.
Implementing a matching of the resulting expressions for the HLbL tensor onto
the perturbative QCD quark loop, we are able to further constrain our
calculation and significantly reduce its model dependence. We find that
especially for the $\pi^0$ the corresponding increase of the HLbL contribution
is much smaller than previous prescriptions in the literature would imply.
Overall, we estimate that longitudinal SDCs increase the HLbL contribution by
$\Delta a_\mu^\text{LSDC}=13(6)\times 10^{-11}$. This number does not include
the contribution from the charm quark, for which we find
$a_\mu^{c\text{-quark}}=3(1)\times 10^{-11}$.
|
[
{
"created": "Tue, 29 Oct 2019 17:49:29 GMT",
"version": "v1"
},
{
"created": "Fri, 13 Mar 2020 16:01:33 GMT",
"version": "v2"
}
] |
2020-03-24
|
[
[
"Colangelo",
"Gilberto",
""
],
[
"Hagelstein",
"Franziska",
""
],
[
"Hoferichter",
"Martin",
""
],
[
"Laub",
"Laetitia",
""
],
[
"Stoffer",
"Peter",
""
]
] |
While the low-energy part of the hadronic light-by-light (HLbL) tensor can be constrained from data using dispersion relations, for a full evaluation of its contribution to the anomalous magnetic moment of the muon $(g-2)_\mu$ also mixed- and high-energy regions need to be estimated. Both can be addressed within the operator product expansion (OPE), either for configurations where all photon virtualities become large or one of them remains finite. Imposing such short-distance constraints (SDCs) on the HLbL tensor is thus a major aspect of a model-independent approach towards HLbL scattering. Here, we focus on longitudinal SDCs, which concern the amplitudes containing the pseudoscalar-pole contributions from $\pi^0$, $\eta$, $\eta'$. Since these conditions cannot be fulfilled by a finite number of pseudoscalar poles, we consider a tower of excited pseudoscalars, constraining their masses and transition form factors from Regge theory, the OPE, and phenomenology. Implementing a matching of the resulting expressions for the HLbL tensor onto the perturbative QCD quark loop, we are able to further constrain our calculation and significantly reduce its model dependence. We find that especially for the $\pi^0$ the corresponding increase of the HLbL contribution is much smaller than previous prescriptions in the literature would imply. Overall, we estimate that longitudinal SDCs increase the HLbL contribution by $\Delta a_\mu^\text{LSDC}=13(6)\times 10^{-11}$. This number does not include the contribution from the charm quark, for which we find $a_\mu^{c\text{-quark}}=3(1)\times 10^{-11}$.
|
0705.0579
|
Fuminobu Takahashi
|
Fuminobu Takahashi
|
Gravitino Dark Matter from Inflaton Decay
|
16 pages, 3 figures. v2: references and figures added
|
Phys.Lett.B660:100-106,2008
|
10.1016/j.physletb.2007.12.048
|
DESY 07-060
|
hep-ph astro-ph hep-th
| null |
We discuss a scenario that gravitinos produced non-thermally by an inflaton
decay constitute dark matter in the present universe. We find that this
scenario is realized for wide ranges of the inflaton mass and the vacuum
expectation value. What is intriguing about this scenario is that the gravitino
dark matter can have a relatively large free streaming length at
matter-radiation equality, which can be probed by future observation on
QSO-galaxy strong lens system.
|
[
{
"created": "Fri, 4 May 2007 18:51:54 GMT",
"version": "v1"
},
{
"created": "Thu, 9 Aug 2007 15:04:38 GMT",
"version": "v2"
}
] |
2008-11-26
|
[
[
"Takahashi",
"Fuminobu",
""
]
] |
We discuss a scenario that gravitinos produced non-thermally by an inflaton decay constitute dark matter in the present universe. We find that this scenario is realized for wide ranges of the inflaton mass and the vacuum expectation value. What is intriguing about this scenario is that the gravitino dark matter can have a relatively large free streaming length at matter-radiation equality, which can be probed by future observation on QSO-galaxy strong lens system.
|
1309.0831
|
Rodolfo A. Diaz
|
Andres Castillo, Rodolfo A. Diaz, John Morales
|
Unitarity constraints for Yukawa couplings in the two Higgs doublet
model type III
|
14 pages, 2 figures, LaTeX2e
|
Int. J. Mod Phys A. Vol. 29, No. 18 (2014) 1450085
|
10.1142/S0217751X14500857
| null |
hep-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Unitarity constraints for Yukawa couplings are considered in the Two Higgs
Doublet Model type III, by using a general expansion in partial waves for
fermionic scattering processes. Constraints over general Flavor Changing
Neutral Currents are found from that systematic, such bounds compete with those
coming from Lagrangian perturbativity requirement but are weaker than those
imposed from phenomenological processes and precision tests. Nevertheless, for
bounds based on unitarity the number of assumptions is the lowest among
phenomenological and theoretical limits. Indeed, these new theoretical
constraints are independent of scalar masses or mixing angles for this extended
Higgs sector, making them less model dependent.
|
[
{
"created": "Tue, 3 Sep 2013 20:22:08 GMT",
"version": "v1"
}
] |
2014-08-07
|
[
[
"Castillo",
"Andres",
""
],
[
"Diaz",
"Rodolfo A.",
""
],
[
"Morales",
"John",
""
]
] |
Unitarity constraints for Yukawa couplings are considered in the Two Higgs Doublet Model type III, by using a general expansion in partial waves for fermionic scattering processes. Constraints over general Flavor Changing Neutral Currents are found from that systematic, such bounds compete with those coming from Lagrangian perturbativity requirement but are weaker than those imposed from phenomenological processes and precision tests. Nevertheless, for bounds based on unitarity the number of assumptions is the lowest among phenomenological and theoretical limits. Indeed, these new theoretical constraints are independent of scalar masses or mixing angles for this extended Higgs sector, making them less model dependent.
|
1410.6284
|
Bai-Song Xie
|
Z. L. Li, D. Lu, B. F. Shen, L. B. Fu, J. Liu, and B. S. Xie
|
Mass shift effects in nonperturbative multiphoton pair production for
arbitrary polarized electric fields
|
14 pages, 6 figures
| null | null | null |
hep-ph quant-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The mass shift effects in multiphoton pair production of a nonperturbative
nature for arbitrary polarized electric fields are investigated numerically by
employing the real-time Dirac-Heisenberg-Wigner formalism, and theoretically by
proposing an effective energy concept. It is found that the theoretical results
are agreement with the numerical ones very well. It is the first time to
consider the roles of the momenta of created particles and the polarizations of
external fields played in the mass shift effects. These results can deepen the
understanding of pair production in the nonperturbative threshold regime.
Moreover, the distinct mass shift effects are observable in the forthcoming
experiments and can be used as a probe to distinguish the electron-positron
pair production from other background events.
|
[
{
"created": "Thu, 23 Oct 2014 08:15:59 GMT",
"version": "v1"
}
] |
2014-10-24
|
[
[
"Li",
"Z. L.",
""
],
[
"Lu",
"D.",
""
],
[
"Shen",
"B. F.",
""
],
[
"Fu",
"L. B.",
""
],
[
"Liu",
"J.",
""
],
[
"Xie",
"B. S.",
""
]
] |
The mass shift effects in multiphoton pair production of a nonperturbative nature for arbitrary polarized electric fields are investigated numerically by employing the real-time Dirac-Heisenberg-Wigner formalism, and theoretically by proposing an effective energy concept. It is found that the theoretical results are agreement with the numerical ones very well. It is the first time to consider the roles of the momenta of created particles and the polarizations of external fields played in the mass shift effects. These results can deepen the understanding of pair production in the nonperturbative threshold regime. Moreover, the distinct mass shift effects are observable in the forthcoming experiments and can be used as a probe to distinguish the electron-positron pair production from other background events.
|
hep-ph/9812408
|
Alexander Ya. Parkhomenko
|
N.V. Mikheev, A.Ya. Parkhomenko and L.A. Vassilevskaya
|
Field-induced axion decay $a \to e^+ e^-$ via plasmon
|
4 pages, latex, 2 PS figures, used espcrc2.sty Talk given at the 5th
IFT Workshop on Axions, 13-15 March 1998, Gainesville, Florida, USA. To be
published in Nucl. Phys. B (Proc. Suppl.)
|
Nucl.Phys.Proc.Suppl. 72 (1999) 58-61
|
10.1016/S0920-5632(98)00503-9
|
YARU-HE-98/08
|
hep-ph
| null |
The axion decay $a \to e^+ e^-$ via a plasmon is investigated in an external
magnetic field. The results we have obtained demonstrate a strong catalyzing
influence of the field as the axion lifetime in the magnetic field of order
$10^{15}$ G and at temperature of order 10 MeV is reduced to $10^4$ sec.
|
[
{
"created": "Thu, 17 Dec 1998 10:14:24 GMT",
"version": "v1"
}
] |
2009-10-31
|
[
[
"Mikheev",
"N. V.",
""
],
[
"Parkhomenko",
"A. Ya.",
""
],
[
"Vassilevskaya",
"L. A.",
""
]
] |
The axion decay $a \to e^+ e^-$ via a plasmon is investigated in an external magnetic field. The results we have obtained demonstrate a strong catalyzing influence of the field as the axion lifetime in the magnetic field of order $10^{15}$ G and at temperature of order 10 MeV is reduced to $10^4$ sec.
|
1704.00935
|
Chunsheng An
|
C. S. An and B. Saghai
|
Intrinsic light and strange quark--antiquark pairs in the proton and
nonperturbative strangeness suppression
|
To appear in Phys. Rev. D
| null |
10.1103/PhysRevD.95.074015
| null |
hep-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The CLAS Collaboration recently reported measured ratios of pion and kaon
electroproduction cross sections from a proton target and extracted the ratios
for light and strange quark--antiquark pairs, ${u\bar{u}}/ {d\bar{d}}$ and
${s\bar{s}}/ {d\bar{d}}$. Within an extended chiral constituent quark
formalism, we investigate contributions to those ratios from the
nonperturbative mechanism due to all possible intrinsic $|uudQ \bar{Q}\rangle$
Fock states in the proton; with $Q \bar{Q} \equiv u\bar{u},~
d\bar{d},~s\bar{s},~c\bar{c}$. Our results are compared with the CLAS data and
findings from other phenomenological approaches, offering insights into the
manifestations of the genuine five--quark Fock states in the proton and its
relevance to interpreting the experimental data.
|
[
{
"created": "Tue, 4 Apr 2017 09:49:26 GMT",
"version": "v1"
}
] |
2017-04-26
|
[
[
"An",
"C. S.",
""
],
[
"Saghai",
"B.",
""
]
] |
The CLAS Collaboration recently reported measured ratios of pion and kaon electroproduction cross sections from a proton target and extracted the ratios for light and strange quark--antiquark pairs, ${u\bar{u}}/ {d\bar{d}}$ and ${s\bar{s}}/ {d\bar{d}}$. Within an extended chiral constituent quark formalism, we investigate contributions to those ratios from the nonperturbative mechanism due to all possible intrinsic $|uudQ \bar{Q}\rangle$ Fock states in the proton; with $Q \bar{Q} \equiv u\bar{u},~ d\bar{d},~s\bar{s},~c\bar{c}$. Our results are compared with the CLAS data and findings from other phenomenological approaches, offering insights into the manifestations of the genuine five--quark Fock states in the proton and its relevance to interpreting the experimental data.
|
2205.08160
|
Aneta Wojnar
|
Aneta Wojnar
|
Stellar and substellar objects in modified gravity
|
20 pages, 1 figure, Invited contribution to the forthcoming book
"Modified and Quantum Gravity - From theory to experimental searches on all
scales", Springer Nature, Eds C. L\"ammerzahl and C. Pfeifer
| null |
10.1007/978-3-031-31520-6
| null |
gr-qc astro-ph.EP astro-ph.SR
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The last findings on stellar and substellar objects in modified gravity are
presented, allowing a reader to quickly jump into this topic. Early stellar
evolution of low-mass stars, cooling models of brown dwarfs and giant gaseous
exoplanets as well as internal structure of terrestrial planets are discussed.
Moreover, possible test of models of gravity with the use of the discussed
objects are proposed.
|
[
{
"created": "Tue, 17 May 2022 07:51:57 GMT",
"version": "v1"
}
] |
2023-11-27
|
[
[
"Wojnar",
"Aneta",
""
]
] |
The last findings on stellar and substellar objects in modified gravity are presented, allowing a reader to quickly jump into this topic. Early stellar evolution of low-mass stars, cooling models of brown dwarfs and giant gaseous exoplanets as well as internal structure of terrestrial planets are discussed. Moreover, possible test of models of gravity with the use of the discussed objects are proposed.
|
0708.0241
|
Serkant Ali Cetin
|
E. Arik (Bogazici Univ., Istanbul, Turkey), S. A. Cetin (Dogus Univ.,
Istanbul, Turkey), S. Sultansoy (TOBB ET Univ., Ankara, Turkey and Institute
of Physics, Baku, Azerbaijan)
|
The impact of the fourth SM family on the Higgs observability at the LHC
|
4pages, 6 figures
|
Balkan Phys.Lett.15N4:1-5,2007
| null | null |
hep-ph
| null |
It is shown that if the fourth SM fermion family exists then the Higgs boson
could be observed at the LHC with an integrated luminosity of few fb-1. The
Higgs discovery potential for different channels is discussed in the presence
of the fourth SM family.
|
[
{
"created": "Wed, 1 Aug 2007 22:34:38 GMT",
"version": "v1"
}
] |
2009-01-01
|
[
[
"Arik",
"E.",
"",
"Bogazici Univ., Istanbul, Turkey"
],
[
"Cetin",
"S. A.",
"",
"Dogus Univ.,\n Istanbul, Turkey"
],
[
"Sultansoy",
"S.",
"",
"TOBB ET Univ., Ankara, Turkey and Institute\n of Physics, Baku, Azerbaijan"
]
] |
It is shown that if the fourth SM fermion family exists then the Higgs boson could be observed at the LHC with an integrated luminosity of few fb-1. The Higgs discovery potential for different channels is discussed in the presence of the fourth SM family.
|
0909.2836
|
Emiliano Molinaro
|
E. Molinaro, S.T. Petcov
|
On the Interplay Between the 'Low' and 'High' Energy CP-Violation in
Leptogenesis
|
Submitted to the proceedings of "The 2009 Europhysics Conference on
High Energy Physics", July 16 - 22, 2009, Krakow, Poland
| null | null | null |
hep-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The CP-violation necessary for the generation of the baryon asymmetry of the
Universe in the "flavoured" leptogenesis scenario can arise from the "low
energy" PMNS neutrino mixing matrix and/or from the "high energy" part of
neutrino Yukawa couplings, which can mediate CP-violating phenomena only at
some high energy scale. The possible interplay between these two types of
CP-violation is discussed. The type I see-saw model with three heavy
right-handed Majorana neutrinos having hierarchical spectrum is considered. The
analysis shows that there exist regions in the leptogenesis parameter space
where the relevant "high energy" phases have large CP-violating values, but the
purely "high energy" contribution to the baryon asymmetry plays a
subdominant/suppressed role in the production of baryon asymmetry compatible
with the observations and one can have successful leptogenesis if the requisite
CP-violation is provided by the Majorana phase(s) in the neutrino mixing
matrix.
|
[
{
"created": "Tue, 15 Sep 2009 16:31:14 GMT",
"version": "v1"
}
] |
2009-09-16
|
[
[
"Molinaro",
"E.",
""
],
[
"Petcov",
"S. T.",
""
]
] |
The CP-violation necessary for the generation of the baryon asymmetry of the Universe in the "flavoured" leptogenesis scenario can arise from the "low energy" PMNS neutrino mixing matrix and/or from the "high energy" part of neutrino Yukawa couplings, which can mediate CP-violating phenomena only at some high energy scale. The possible interplay between these two types of CP-violation is discussed. The type I see-saw model with three heavy right-handed Majorana neutrinos having hierarchical spectrum is considered. The analysis shows that there exist regions in the leptogenesis parameter space where the relevant "high energy" phases have large CP-violating values, but the purely "high energy" contribution to the baryon asymmetry plays a subdominant/suppressed role in the production of baryon asymmetry compatible with the observations and one can have successful leptogenesis if the requisite CP-violation is provided by the Majorana phase(s) in the neutrino mixing matrix.
|
hep-ph/0307033
|
Robert Fleischer
|
Robert Fleischer (CERN)
|
CP Violation and New Physics in $B_s$ Decays
|
10 pages, LaTeX. Invited talk at FPCP 2003, Paris, France, 3-6 June
2003. To appear in the Proceedings. Reference added
|
ECONF C030603:MAR16,2003
| null |
CERN-TH/2003-149
|
hep-ph
| null |
The $B_s$-meson system is a key element in the $B$-physics programme of
hadron colliders, offering various avenues to explore CP violation and to
search for new physics. One of the most prominent decays is $B_s\to
J/\psi\phi$, the counterpart of $B_d\to J/\psi K_S$, providing a powerful tool
to search for new-physics contributions to $B^0_s$--$\bar{B^0_s}$ mixing.
Another benchmark mode is $B_s\to K^+K^-$, which complements
$B_d\to\pi^+\pi^-$, thereby allowing an extraction of the angle $\gamma$ of the
unitarity triangle that is sensitive to new-physics effects in the QCD penguin
sector. Finally, we discuss new methods to constrain and determine $\gamma$
with the help of $B_s\to D_s^{(\ast)\pm} K^\mp$ decays, which complement
$B_d\to D^{(\ast)\pm}\pi^\mp$ modes. Since these strategies involve ``tree''
decays, the values of $\gamma$ thus extracted exhibit a small sensitivity on
new physics.
|
[
{
"created": "Wed, 2 Jul 2003 14:32:29 GMT",
"version": "v1"
},
{
"created": "Fri, 4 Jul 2003 08:36:33 GMT",
"version": "v2"
}
] |
2010-11-23
|
[
[
"Fleischer",
"Robert",
"",
"CERN"
]
] |
The $B_s$-meson system is a key element in the $B$-physics programme of hadron colliders, offering various avenues to explore CP violation and to search for new physics. One of the most prominent decays is $B_s\to J/\psi\phi$, the counterpart of $B_d\to J/\psi K_S$, providing a powerful tool to search for new-physics contributions to $B^0_s$--$\bar{B^0_s}$ mixing. Another benchmark mode is $B_s\to K^+K^-$, which complements $B_d\to\pi^+\pi^-$, thereby allowing an extraction of the angle $\gamma$ of the unitarity triangle that is sensitive to new-physics effects in the QCD penguin sector. Finally, we discuss new methods to constrain and determine $\gamma$ with the help of $B_s\to D_s^{(\ast)\pm} K^\mp$ decays, which complement $B_d\to D^{(\ast)\pm}\pi^\mp$ modes. Since these strategies involve ``tree'' decays, the values of $\gamma$ thus extracted exhibit a small sensitivity on new physics.
|
1901.08243
|
Nikolaos Dimakis
|
T. Pailas, N. Dimakis, A. Karagiorgos, Petros A. Terzis, G.O.
Papadopoulos and T. Christodoulakis
|
Classical and quantum analysis of 3D electromagnetic pp-wave spacetime
|
27 pages, no figures, updated to match the CQG published version
| null |
10.1088/1361-6382/ab2561
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The general classical solution of the 3D electromagnetic pp-wave spacetime
has been obtained. The relevant line element contains an arbitrary essential
function providing an infinite number of in-equivalent geometries as solutions.
A classification is presented based on the symmetry group. To the best of our
knowledge, the solution corresponding to only one of the Classes is known. The
dynamics of some of the Classes was also derived from a minisuperspace
Lagrangian which has been constructed. This Lagrangian contains a degree of
freedom (the lapse) which can be considered either as dynamical or
non-dynamical (indicating a singular or a regular Lagrangian correspondingly).
Surprisingly enough, on the space of classical solutions, an equivalence of
these two points of view can be established. The canonical quantization is then
used in order to quantize the system for both the singular and regular
Hamiltonian. A subsequent interpretation of quantum states is based on a
Bohm-like analysis. The semi-classical trajectories deviate from the classical
only for the regular Hamiltonian and in particular for a superposition of
eigenstates (a Gaussian initial state has been used). Thus, the above mentioned
equivalence is broken at the quantum level. It is noteworthy that the
semi-classical trajectories tend to the classical ones in the limit where the
initial wavepacket is widely spread. Hence, even with this simple superposition
state, the classical solutions are acquired as a limit of the semi-classical.
|
[
{
"created": "Thu, 24 Jan 2019 06:00:02 GMT",
"version": "v1"
},
{
"created": "Thu, 30 May 2019 02:47:52 GMT",
"version": "v2"
}
] |
2019-05-31
|
[
[
"Pailas",
"T.",
""
],
[
"Dimakis",
"N.",
""
],
[
"Karagiorgos",
"A.",
""
],
[
"Terzis",
"Petros A.",
""
],
[
"Papadopoulos",
"G. O.",
""
],
[
"Christodoulakis",
"T.",
""
]
] |
The general classical solution of the 3D electromagnetic pp-wave spacetime has been obtained. The relevant line element contains an arbitrary essential function providing an infinite number of in-equivalent geometries as solutions. A classification is presented based on the symmetry group. To the best of our knowledge, the solution corresponding to only one of the Classes is known. The dynamics of some of the Classes was also derived from a minisuperspace Lagrangian which has been constructed. This Lagrangian contains a degree of freedom (the lapse) which can be considered either as dynamical or non-dynamical (indicating a singular or a regular Lagrangian correspondingly). Surprisingly enough, on the space of classical solutions, an equivalence of these two points of view can be established. The canonical quantization is then used in order to quantize the system for both the singular and regular Hamiltonian. A subsequent interpretation of quantum states is based on a Bohm-like analysis. The semi-classical trajectories deviate from the classical only for the regular Hamiltonian and in particular for a superposition of eigenstates (a Gaussian initial state has been used). Thus, the above mentioned equivalence is broken at the quantum level. It is noteworthy that the semi-classical trajectories tend to the classical ones in the limit where the initial wavepacket is widely spread. Hence, even with this simple superposition state, the classical solutions are acquired as a limit of the semi-classical.
|
hep-ph/0002040
|
Dmitry Matsukevich
|
V. G. Baryshevsky, D. N. Matsukevich
|
Time-reversal violating rotation of polarization plane of light in gas
placed in the electric field
|
13 pages, 2 Postscript figures, misprint corrected
| null | null | null |
hep-ph
| null |
The rotation of polarization plane of light in a gas placed in the electric
field is considered. Different mechanisms that cause this phenomenon are
investigated. Angle of polarization plane rotation for transition 6S_{1/2} ->
7S_{1/2} in cesium is estimated. The possibility to observe this effect in
experiment is discussed.
|
[
{
"created": "Thu, 3 Feb 2000 16:22:19 GMT",
"version": "v1"
},
{
"created": "Thu, 10 Feb 2000 15:59:31 GMT",
"version": "v2"
}
] |
2007-05-23
|
[
[
"Baryshevsky",
"V. G.",
""
],
[
"Matsukevich",
"D. N.",
""
]
] |
The rotation of polarization plane of light in a gas placed in the electric field is considered. Different mechanisms that cause this phenomenon are investigated. Angle of polarization plane rotation for transition 6S_{1/2} -> 7S_{1/2} in cesium is estimated. The possibility to observe this effect in experiment is discussed.
|
hep-ph/0609130
|
Lorenzo Ravagli
|
Lorenzo Ravagli
|
A study of meson condensation and of the QCD critical line
|
PhD thesis (Advisor Dr. Giulio Pettini), Feb 2006
| null | null |
DFF 434/09/06
|
hep-ph
| null |
In this thesis work we have employed two microscopic models (ladder-QCD and
Nambu-Jona-Lasinio) for describing the properties of the QCD phase diagram at
finite temperature and quark densities. In particular, we have studied the
mechanism of meson condensation at finite isospin and strangeness chemical
potentials, and its competition with ``standard'' scalar fermionic condensates.
In the last chapter, a detailed study of the chiral critical line at finite
chemical potentials has been performed, achieving a remarkable agreement with
recent lattice data.
|
[
{
"created": "Wed, 13 Sep 2006 15:20:30 GMT",
"version": "v1"
}
] |
2009-09-29
|
[
[
"Ravagli",
"Lorenzo",
""
]
] |
In this thesis work we have employed two microscopic models (ladder-QCD and Nambu-Jona-Lasinio) for describing the properties of the QCD phase diagram at finite temperature and quark densities. In particular, we have studied the mechanism of meson condensation at finite isospin and strangeness chemical potentials, and its competition with ``standard'' scalar fermionic condensates. In the last chapter, a detailed study of the chiral critical line at finite chemical potentials has been performed, achieving a remarkable agreement with recent lattice data.
|
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