pinecone/core-2020-05-10-deduplication huggingface dataset:
Horizon problem in a closed universe dominated by fluid with negative
  pressure

We discuss the horizon problem in a universe dominated by fluid with negative
pressure. We show that for generally accepted value of nonrelativistic matter
energy density parameter $\Omega_{m0}<1$, the horizon problem can be solved
only if the fluid influencing negative pressure (the so-called ``X'' component)
violates the point-wise strong energy condition and if its energy density is
sufficiently large $(\Omega_{X 0}>1)$. The calculated value of the
$\Omega_{X0}$ parameter allowing for the solution of the horizon problem is
confronted with some recent observational data. Assuming that $p_X/\rho_X<-0.6$
we find that the required amount of the ``X'' component is not ruled out by the
supernova limits. Since the value of energy density parameter $\Omega_{v0}$ for
cosmological constant larger than 1 is excluded by gravitational lensing
observations the value of the ratio $p_X/\rho_X$ should lie between the values
-1 and -0.6 if the model has to be free of the horizon problem beeing at the
same time consistent with observations. The value of $\Omega_{X0}+\Omega_{m0}$
in the model is consistent with the constraints $0.2<\Omega_{\text{tot}}<1.5$
following from cosmic microwave background observations provided that
$\Omega_{m0}$ is low ($<0.2$).Comment: 18 pages, revtex3.1, 5 encapsulated figure
Numerical results for two interacting particles in a random environment

Much evidence has been collected to date which shows that repulsive
electron-electron interaction can lead to the formation of particle pairs in a
one-dimensional random energy landscape. The localization length \lambda_2 of
these pair states is finite, but larger than the localization length \lambda_1
of the individual particles. After a short review of previous work, we present
numerical evidence for this effect based on an analysis of the interaction
matrix elements and an application of the decimation method. The results based
on the decimation method for a two-dimensional disordered medium support the
localization-delocalization transition of pair states predicted recently.Comment: 10 pages including 8 EPS/PS figures, uses annalen.cls (included), to
  appear in Ann. Phys. (Leipzig) 8, (1999) for the Proceedings of "Localisation
  99
Measurement of Masses and Widths of Excited Charm Mesons $D_2^*$ and
  Evidence for Broad States

Using data from the FOCUS experiment we analyze the $D^+\pi^-$ and $D^0\pi^+$
invariant mass distributions. We measure the $D_2^{*0}$ mass $M_{D_2^{*0}} =
(2464.5 \pm 1.1 \pm 1.9) \mev$ and width $\Gamma_{D_2^{*0}} = (38.7 \pm 5.3 \pm
2.9) \mev$, and the $D_2^{*+}$ mass $ M_{D_2^{*+}} = (2467.6 \pm 1.5 \pm 0.76)
\mev$ and width $ \Gamma_{D_2^{*+}} = (34.1 \pm 6.5 \pm 4.2) \mev$. We find
evidence for broad structures over background in both the neutral and charged
final state. If each is interpreted as evidence for a single L=1, $j_q=1/2$
excited charm meson resonance, the masses and widths are $M_{1/2}^0 =(2407 \pm
21 \pm 35) \mev$, $\Gamma_{1/2}^0 = (240 \pm 55 \pm 59) \mev$, and $M_{1/2}^+ =
(2403 \pm 14 \pm 35) \mev$ $\Gamma_{1/2}^+ = (283 \pm 24 \pm 34) \mev$,
respectively.Comment: 15 pages, 4 figures. Submitted to Phys. Lett. B. Added preprint
  number
Spin alignment of leading K*(892)^0 mesons in hadronic Z^0 decays

Helicity density matrix elements for inclusive K*(892)^0 mesons from hadronic
Z^0 decays have been measured over the full range of K^*0 momentum using data
taken with the OPAL experiment at LEP. A preference for occupation of the
helicity zero state is observed at all scaled momentum x_p values above 0.3,
with the matrix element rho_00 rising to 0.66 +/- 0.11 for x_p > 0.7. The
values of the real part of the off-diagonal element rho_1-1 are negative at
large x_p, with a weighted average value of -0.09 +/- 0.03 for x_p > 0.3, in
agreement with new theoretical predictions based on Standard Model parameters
and coherent fragmentation of the qq(bar) system from the Z^0 decay. All other
helicity density matrix elements measured are consistent with zero over the
entire x_p range. The K^*0 fragmentation function has also been measured and
the total rate determined to be 0.74 +/- 0.02 +/- 0.02 K*(892)^0 mesons per
hadronic Z^0 decay.Comment: 19 pages, LaTeX, uses a4p.sty, pennames.sty, 4 eps figures included,
  submitted to Phys. Lett.
A new method for extracting the bottom quark Yukawa coupling at the CERN
  Large Hadron Collider

We propose a new method for measuring the H -> bb rate at the CERN LHC in a
manner which would allow extraction of the b quark Yukawa coupling. Higgs boson
production in purely electroweak WHjj events is calculated. The Standard Model
signal rate including decays W -> l nu and H -> bb is 11 fb for M_H = 120 GeV.
It is possible to suppress the principal backgrounds, Wbbjj and ttjj, to
approximately the level of the signal. As the top quark Yukawa coupling does
not appear in this process, it promises a reliable extraction of g_Hbb in the
context of the Standard Model or some extensions, such as the MSSM.Comment: added background, updated/added references, additional comment
Non-perturbative gluons in diffractive photo-production of J/Psi

The modifications induced in the calculation of the cross section of the
diffractive process gamma gamma -> J/Psi J/Psi when the gluon propagator is
changed are analyzed. Instead of the usual perturbative gluon propagator,
alternative forms obtained using non-perturbative methods like Dyson-Schwinger
equations are used to consider in a more consistent way the contributions of
the infrared region. The result shows a reduction in the differential
cross-section for low momentum transfer once compared with the perturbative
result, to be confirmed with future experimental results from TESLA.Comment: 17 pages, 5 figures, RevTex, Accepted for publication in Phys. Lett.
Threshold corrections to m_b and the b\bar{b} -> H^0_i production in
  CP-violating SUSY scenarios

The inclusion of supersymmetric threshold corrections to the $b$-quark mass
has dramatic consequences in scenarios with large CP-mixing effects in the
Higgs sector. In particular, when the phase of the combination
$M_{\tilde{g}}\mu$ is $\sim 180^{\rm o} \pm 30^{\rm o}$, the lightest-sbottom
squark becomes tachyonic and, possibly, the $b$-quark Yukawa coupling
nonperturbative for values of $\tan \beta$ ranging from intermediate up to
large or very large, depending on the size of $arg(A_t\mu)$, $arg(A_b\mu)$, and
the details of the spectrum. For these scenarios, when allowed, as well as
scenarios with different values of $arg(M_{\tilde{g}}\mu)$, the cross sections
for the production of the three neutral-Higgs bosons through $b$-quark have
rather interesting dependences on $arg(A_t\mu)$ and $arg(A_b\mu)$, and the
deviations induced by the $m_b$ corrections are rather large. In general, such
production channel cannot be neglected with respect to the production through
gluon fusion. For large CP-mixing effects, the lightest neutral-Higgs boson can
be mainly CP odd and the $b$-quark fusion becomes its main production
mechanism. Searches at the Tevatron and the LHC can easily detect such a Higgs
boson, or constrain the CP-violating scenarios that allow it.Comment: 1+15 pages, 5 figures, References added. Extended discussion of the
  b-b-Higgs couplings, to appear in Phys. Lett.
A (2+1) non-commutative Drinfel'd double spacetime with cosmological
  constant

We show that the Drinfel'd double associated to the standard quantum
deformation $sl_\eta(2,R)$ is isomorphic to the (2+1)-dimensional AdS algebra
with the initial deformation parameter $\eta$ related to the cosmological
constant $\Lambda=-\eta^2$. This gives rise to a generalisation of a
non-commutative Minkowski spacetime that arises as a consequence of the quantum
double symmetry of (2+1) gravity to non-vanishing cosmological constant. The
properties of the AdS quantum double that generalises this symmetry to the case
$\Lambda\neq 0$ are sketched, and it is shown that the new non-commutative AdS
spacetime is a nonlinear $\Lambda$-deformation of the Minkowskian one.Comment: 14 pages; some comments and references adde
Moment Analysis of Hadronic Vacuum Polarization - Proposal for a lattice
  QCD evaluation of $g_{\mu}-2$

I suggest a new approach to the determination of the hadronic vacuum
polarization (HVP) contribution to the anomalous magnetic moment of the muon
$a_{\mu}^{\rm HVP}$ in lattice QCD. It is based on properties of the Mellin
transform of the hadronic spectral function and their relation to the HVP self
energy in the Euclidean. I show how $a_{\mu}^{\rm HVP}$ is very well
approximated by a few moments associated to this Mellin transform and how these
moments can be evaluated in lattice QCD, providing thus a series of tests when
compared with the corresponding determinations using experimental data
Dilatonic formulation for conducting cosmic string models

It is shown how the the introduction of a suitably defined dilatonic
auxiliary field, $\Phi$ say, makes it possible for the non-linear Lagrangian
for a generic elastic string model, of the kind appropriate for representing
superconducting cosmic strings, to be converted into a standardised form as the
sum of a kinetic term that is just homogeneously quadratic in the relevant
scalar phase gradient (as in a simple linear model) together with a potential
energy term, $V$ say, that is specified as a generically non-linear function of
$\Phi$. The explicit form of this function is derived for various noteworthy
examples, of which the most memorable is that of the transonic string model, as
characterised by a given mass scale, $m$ say, for which this potential energy
density will be expressible in terms of the zero current limit value
$\Phi_{_0}$ of $\Phi$ by $ V= {1\over 2} m \big(\Phi_{_0}^{-2} \Phi^2+
\Phi_{_0}^{2} \Phi^{-2} \big)$.Comment: 15 pages Latex. Invited contrib. to JR99 (Weimar), to be published in
  Annalen der Physik (Leipzig
Production Properties of the Orbitally Excited Mesons $f_{0}(980)$, $f_{2}(1270)$, $K^{*0}_{2}(1430)$ and $f'_{2}(1525)$ in $Z^{0}$ Hadronic Decays

DELPHI results are presented on the inclusive production of the neutral mesons rho^0, f_0(980), f_2(1270), K^*0_2(1430) and f'_2(1525) in hadronic Z^0 decays. They are based on about 2 million multihadronic events collected in 1994 and 1995, using the particle identification capabilities of the DELPHI Ring Imaging Cherenkov detectors and measured ionization losses in the Time Projection Chamber. The total production rates per hadronic Z^0 decay have been determined to be: 1.19 +/- 0.10 for rho^0; 0.164 +/- 0.021 for f_0(980); 0.214 +/- 0.038 for f_2(1270); 0.073 +/- 0.023 for K^*0_2(1430); and 0.012 +/- 0.006 for f'_2(1525). The total production rates for all mesons and differential cross-sections for the rho^0, f_0(980) and f_2(1270) are compared with the results of other LEP experiments and with models
An index theorem for Wiener--Hopf operators

We study multivariate generalisations of the classical Wiener--Hopf algebra,
which is the C$^*$-algebra generated by the Wiener--Hopf operators, given by
the convolutions restricted to convex cones. By the work of Muhly and Renault,
this C$^*$-algebra is known to be isomorphic to the reduced C$^*$-algebra of a
certain restricted action groupoid. In a previous paper, we have determined a
composition series of this C$^*$-algebra, and compute the $K$-theory
homomorphisms induced by the `symbol' maps given by the subquotients of the
composition series in terms of the analytical index of a continuous family of
Fredholm operators. In this paper, we obtain a topological expression for these
index maps in terms of geometric-topological data naturally associated to the
underlying convex cone. The resulting index formula is expressed in the
framework of Kasparov's bivariant $KK$-theory. Our proof relies heavily on
groupoid methods.Comment: 46 pages, 1 figure; last version prior to publication, journal
  reference adde
Nuclear structure of 178Hf related to the spin-16, 31-year isomer

The projected shell model is used to study the multi-quasiparticle and
collective excitations of 178Hf. With an axially symmetric basis, the spin-16
isomer at 2.4 MeV appears to be well separated in energy/spin space from other
configurations. However, projected energy surface calculations suggest that
178Hf has significant softness to axially asymmetric shapes, which can strongly
modify the level distribution. The implications for photodeexitation of the
isomer are discussed.Comment: 8 pages, 4 figure
23 GHz VLBI Observations of SN 2008ax

We report on phase-referenced 23 GHz Very-Long-Baseline-Interferometry (VLBI) observations of the type IIb supernova SN 2008ax, made with the Very Long Baseline Array (VLBA) on 2 April 2008 (33 days after explosion). These observations resulted in a marginal detection of the supernova. The total ﬂux density recoveredfrom our VLBI image is \(0.8 \pm 0.3 mJy\) (one standard deviation). As it appears, the structure may be interpreted as either a core-jet or a double source. However, the supernova structure could be somewhat confused with a possible close by noise peak. In such a case, the recovered ﬂux density would decrease to \(0.48 \pm 0.12 mJy\), compatible with the ﬂux densities measured with the VLA at epochs close in time to our VLBI observations. The lowest average expansion velocities derived from our observations are \((1.90 \pm 0.30) \times 10^{5} km\) \(s^{-1}\) (case of a double source) and \((5.2 \pm 1.3) \times 10^{4} km\) \(s^{-1}\) (taking the weaker source component as a spurious, close by, noise peak, which is the more likely interpretation). These velocities are 7.3 and 2 times higher, respectively, than the maximum ejecta velocity inferred from optical-line observations.Astronom
Studying the Perturbed Wess-Zumino-Novikov-Witten SU(2)k Theory Using
  the Truncated Conformal Spectrum Approach

We study the $SU(2)_k$ Wess-Zumino-Novikov-Witten (WZNW) theory perturbed by
the trace of the primary field in the adjoint representation, a theory
governing the low-energy behaviour of a class of strongly correlated electronic
systems. While the model is non-integrable, its dynamics can be investigated
using the numerical technique of the truncated conformal spectrum approach
combined with numerical and analytical renormalization groups (TCSA+RG). The
numerical results so obtained provide support for a semiclassical analysis
valid at $k\gg 1$. Namely, we find that the low energy behavior is sensitive to
the sign of the coupling constant, $\lambda$. Moreover for $\lambda>0$ this
behavior depends on whether $k$ is even or odd. With $k$ even, we find
definitive evidence that the model at low energies is equivalent to the massive
$O(3)$ sigma model. For $k$ odd, the numerical evidence is more equivocal, but
we find indications that the low energy effective theory is critical.Comment: 30 pages, 19 eps figures, LaTeX2e file. Version 2: manuscript
  accepted for publication; small changes in text and in one of the figure
Angular momentum redistribution by mixed modes in evolved low-mass
  stars. I. Theoretical formalism

Seismic observations by the space-borne mission \emph{Kepler} have shown that
the core of red giant stars slows down while evolving, requiring an efficient
physical mechanism to extract angular momentum from the inner layers. Current
stellar evolution codes fail to reproduce the observed rotation rates by
several orders of magnitude, and predict a drastic spin-up of red giant cores
instead. New efficient mechanisms of angular momentum transport are thus
required.
  In this framework, our aim is to investigate the possibility that mixed modes
extract angular momentum from the inner radiative regions of evolved low-mass
stars. To this end, we consider the Transformed Eulerian Mean (TEM) formalism,
introduced by Andrews \& McIntyre (1978), that allows us to consider the
combined effect of both the wave momentum flux in the mean angular momentum
equation and the wave heat flux in the mean entropy equation as well as their
interplay with the meridional circulation.
  In radiative layers of evolved low-mass stars, the quasi-adiabatic
approximation, the limit of slow rotation, and the asymptotic regime can be
applied for mixed modes and enable us to establish a prescription for the wave
fluxes in the mean equations. The formalism is finally applied to a $1.3
M_\odot$ benchmark model, representative of observed CoRoT and \emph{Kepler}
oscillating evolved stars.
  We show that the influence of the wave heat flux on the mean angular momentum
is not negligible and that the overall effect of mixed modes is to extract
angular momentum from the innermost region of the star. A quantitative and
accurate estimate requires realistic values of mode amplitudes. This is
provided in a companion paper.Comment: Accepted in A&A, 11 pages, and 6 figure
Instanton Operators and the Higgs Branch at Infinite Coupling

The richness of 5d $\mathcal{N}=1$ theories with a UV fixed point at infinite
coupling is due to the existence of local disorder operators known as instanton
operators. By considering the Higgs branch of $SU(2)$ gauge theories with $N_f
\leq 7$ flavours at finite and infinite coupling, we write down the explicit
chiral ring relations between instanton operators, the glueball superfield and
mesons. Exciting phenomena appear at infinite coupling: the glueball superfield
is no longer nilpotent and the classical chiral ring relations are quantum
corrected by instanton operators bilinears. We also find expressions for the
dressing of instanton operators of arbitrary charge. The same analysis is
performed for $USp(2k)$ with an antisymmetric hypermultiplet and pure $SU(N)$
gauge theories.Comment: v1: 35 pages + appendices. v2: published version with several
  changes, 37 pages + appendice
QCD corrections to $B \to \pi$ form factors from light-cone sum rules

We compute perturbative corrections to $B \to \pi$ form factors from QCD
light-cone sum rules with $B$-meson distribution amplitudes. Applying the
method of regions we demonstrate factorization of the vacuum-to-$B$-meson
correlation function defined with an interpolating current for pion, at
one-loop level, explicitly in the heavy quark limit. The short-distance
functions in the factorization formulae of the correlation function involves
both hard and hard-collinear scales; and these functions can be further
factorized into hard coefficients by integrating out the hard fluctuations and
jet functions encoding the hard-collinear information. Resummation of large
logarithms in the short-distance functions is then achieved via the standard
renormalization-group approach. We further show that structures of the
factorization formulae for $f_{B \pi}^{+}(q^2)$ and $f_{B \pi}^{0}(q^2)$ at
large hadronic recoil from QCD light-cone sum rules match that derived in QCD
factorization. In particular, we perform an exploratory phenomenological
analysis of $B \to \pi$ form factors, paying attention to various sources of
perturbative and systematic uncertainties, and extract $|V_{ub}|=
\left(3.05^{+0.54}_{-0.38} |_{\rm th.} \pm 0.09 |_{\rm exp.}\right) \times
10^{-3}$ with the inverse moment of the $B$-meson distribution amplitude
$\phi_B^{+}(\omega)$ determined by reproducing $f_{B \pi}^{+}(q^2=0)$ obtained
from the light-cone sum rules with $\pi$ distribution amplitudes. Furthermore,
we present the invariant-mass distributions of the lepton pair for $B \to \pi
\ell \nu_{\ell}$ ($\ell= \mu \,, \tau$) in the whole kinematic region. Finally,
we discuss non-valence Fock state contributions to the $B \to \pi$ form factors
$f_{B \pi}^{+}(q^2)$ and $f_{B \pi}^{0}(q^2)$ in brief.Comment: 44 pages, 12 figure
A New Construction of Calabi-Yau Manifolds: Generalized CICYs

We present a generalization of the complete intersection in products of
projective space (CICY) construction of Calabi-Yau manifolds. CICY three-folds
and four-folds have been studied extensively in the physics literature. Their
utility stems from the fact that they can be simply described in terms of a
`configuration matrix', a matrix of integers from which many of the details of
the geometries can be easily extracted. The generalization we present is to
allow negative integers in the configuration matrices which were previously
taken to have positive semi-definite entries. This broadening of the complete
intersection construction leads to a larger class of Calabi-Yau manifolds than
that considered in previous work, which nevertheless enjoys much of the same
degree of calculational control. These new Calabi-Yau manifolds are complete
intersections in (not necessarily Fano) ambient spaces with an effective
anticanonical class. We find examples with topology distinct from any that has
appeared in the literature to date. The new manifolds thus obtained have many
interesting features. For example, they can have smaller Hodge numbers than
ordinary CICYs and lead to many examples with elliptic and K3-fibration
structures relevant to F-theory and string dualities.Comment: 52 page
“God made the soil, but we made it fertile”: gender, knowledge, and practice in the formation and use of African dark earths in Liberia and Sierra Leone

This paper describes West African farming practices and knowledge that lead to the formation of carbon-rich high-fertility African Dark Earths (AfDE) – human-made soils analogous to Amazonian terra preta, yet subject to continuing production and use. Gender relations and women’s roles are central to how these soils are produced and used. Through social and ecological field studies in Liberia and Sierra Leone we detail how AfDE formation and associated knowledge is gender-differentiated, the central roles of women’s deposition of charred organic materials from cooking, oil palm processing and potash production in producing AfDE, and the gendered dynamics of AfDE use and distribution in the landscape. Different species are cultivated in AfDE compared to non-anthropogenic soils, and AfDE are differentially valued by women and men for horticultural and tree crops. The spatial distribution of AfDE across the landscape reflects shifting household, marriage and settlement practices. Gender relations, subjectivities and interdependencies and the ecology of soils and landscapes mutually shape one another. National policymakers and NGOs planning or managing agricultural carbon projects in West Africa should attend to the knowledge and practices of Loma and Mende women and men who have made and cultivated carbon-rich anthropogenic soils in the region for generations