pinecone/core-2020-05-10-deduplication huggingface dataset:
Interaction of the Particle with the String in Pole-Dipole Approximation

Within the framework of generalized Papapetrou method, we derive the
effective equations of motion for a string with two particles attached to its
ends, along with appropriate boundary conditions. The equations of motion are
the usual Nambu-Goto-like equations, while boundary conditions turn out to be
equations of motion for the particles at the string ends. The form of those
equations is discussed, and they are explicitly solved for a particular case of
a straight-line string rotating around its center. From this solution we obtain
the correction terms to the $J\propto E^2$ law describing Regge trajectories,
due to nonzero angular momenta of the particles.Comment: Proceedings of the BW2007 conference, 5 page
Gravitons, induced geometry and expectation value formalism at finite
  temperature

After establishing the positivity constraint and spin content of the theory
for gravitons interacting with a necessarily, and \textit{a priori},
\textit{non}-conserved external energy-momentum tensor, the expectation value
formalism of the theory is developed at \textit{finite} temperature in the
functional \textit{differential} treatment of quantum field theory. The
necessity of having, \textit{a priori}, a non-conserved external
energy-momentum tensor is an obvious technical requirement so that its
respective ten components may be varied \textit{independently} in order to
generate expectation values and non-linearities in the theory. The covariance
of the \textit{induced} Riemann curvature tensor, in the initial vacuum, is
established even for the quantization in a gauge corresponding only to two
physical states of the gravitons as established above. As an application, the
\textit{induced} correction to the metric and the underlying geometry is
investigated due to a closed string arising from the Nambu action as a solution
of a circularly oscillating string as, perhaps, the simplest generalization of
a limiting point-like object. Finally it is discussed on why the geometry of
spacetime may, in general, depend on temperature due to radiative corrections
and its physical significance is emphasized.Comment: 20 page
Constraints from F and D supersymmetry breaking in general supergravity theories

We study the conditions under which a generic supergravity model involving chiral and vector multiplets can admit vacua with spontaneously broken supersymmetry and realistic cosmological constant. We find that the existence of such viable vacua implies some constraints involving the curvature tensor of the scalar geometry and the charge and mass matrices of the vector fields, and also that the vector of F and D auxiliary fields defining the Goldstino direction is constrained to lie within a certain domain. We illustrate the relevance of these results through some examples and also discuss the implications of our general results on the dynamics of moduli fields in string models. This contribution is based on [1,2,3]
Flux Compactifications of String Theory on Twisted Tori

Global aspects of Scherk-Schwarz dimensional reduction are discussed and it
is shown that it can usually be viewed as arising from a compactification on
the compact space obtained by identifying a (possibly non-compact) group
manifold G under a discrete subgroup Gamma, followed by a truncation. This
allows a generalisation of Scherk-Schwarz reductions to string theory or
M-theory as compactifications on G/Gamma, but only in those cases in which
there is a suitable discrete subgroup of G. We analyse such compactifications
with flux and investigate the gauge symmetry and its spontaneous breaking. We
discuss the covariance under O(d,d), where d is the dimension of the group G,
and the relation to reductions with duality twists. The compactified theories
promote a subgroup of the O(d,d) that would arise from a toroidal reduction to
a gauge symmetry, and we discuss the interplay between the gauge symmetry and
the O(d,d,Z) T-duality group, suggesting the role that T-duality should play in
such compactifications.Comment: 43 page
Local Grand Unification in the Heterotic Landscape

We consider the possibility that the unification of the electroweak
interactions and the strong force arises from string theory, at energies
significantly lower than the string scale. As a tool, an effective grand
unified field theory in six dimensions is derived from an anisotropic orbifold
compactification of the heterotic string. It is explicitly shown that all
anomalies cancel in the model, though anomalous Abelian gauge symmetries are
present locally at the boundary singularities. In the supersymmetric vacuum
additional interactions arise from higher-dimensional operators. We develop
methods that relate the couplings of the effective theory to the location of
the vacuum, and find that unbroken discrete symmetries play an important role
for the phenomenology of orbifold models. An efficient algorithm for the
calculation of the superpotential to arbitrary order is developed, based on
symmetry arguments. We furthermore present a correspondence between bulk fields
of the orbifold model in six dimensions, and the moduli fields that arise from
compactifying four internal dimensions on a manifold with non-trivial gauge
background.Comment: 141 pages, 6 figures, Ph.D. thesi
Quantum 2-Body Hamiltonian for Topological Color Codes

We introduce a two-body quantum Hamiltonian model with spins-$\half$ located
on the vertices of a 2D spatial lattice. The model exhibits an exact
topological degeneracy in all coupling regimes. This is a remarkable
non-perturbative effect. The model has a $\Z_2\times \Z_2$ gauge group symmetry
and string-net integrals of motion. There exists a gapped phase in which the
low-energy sector reproduces an effective topological color code model. High
energy excitations fall into three families of anyonic fermions that turn out
to be strongly interacting. All these, and more, are new features not present
in honeycomb lattice models like Kitaev model.Comment: Cotribution to the Proceedings of the Scala Conference 2009 (Cortina,
  Italy). Special Issue dedicated to Prof. Prof. Tombesi, on occasion of his
  seventieth birthday. Editors: D. Vitali, I Marzoli, S. Mancini, G. Di
  Giuseppe. "Fortschritte der Physik
Entanglement and symmetry effects in the transition to the Schroedinger
  cat regime

We study two-spin entanglement and order parameter fluctuations as a function
of the system size in the XY model in a transverse field and in the isotropic
XXX model. Both models are characterized by the occurrence of ground state
degeneracy also when systems of finite size are considered. This is always true
for the XXX model, but only at the factorizing field for the XY model. We study
the size dependence of symmetric states, which, in the presence of degeneracy,
can be expanded as a linear combination of broken symmetry states. We show
that, while the XY model looses its quantum superposition content exponentially
with the size $N$, a decrease of the order of 1/N is observed when the XXX
model is considered. The emergence of two qualitatively different regimes is
directly related to the difference in the symmetry of the models
Dual linearized gravity in D=6 coupled to a purely spin-two field of
  mixed symmetry (2,2)

Under the hypotheses of analyticity, locality, Lorentz covariance, and
Poincare invariance of the deformations, combined with the requirement that the
interaction vertices contain at most two spatiotemporal derivatives of the
fields, we investigate the consistent interactions between a single massless
tensor field with the mixed symmetry (3,1) and one massless tensor field with
the mixed symmetry (2,2). The computations are done with the help of the
deformation theory based on a cohomological approach, in the context of the
antifield-BRST formalism. Our result is that dual linearized gravity in D=6
gets coupled to a purely spin-two field with the mixed symmetry of the Riemann
tensor such that both the gauge transformations and first-order reducibility
relations in the (3,1) sector are changed, but not the gauge algebra.Comment: 35 page
On the Problem of Renormalizability in Non-Commutative Gauge Field
  Models - A Critical Review

When considering quantum field theories on non-commutative spaces one
inevitably encounters the infamous UV/IR mixing problem. So far, only very few
renormalizable models exist and all of them describe non-commutative scalar
field theories on four-dimensional Euclidean Groenewold-Moyal deformed space,
also known as `theta-deformed space'. In this work we discuss some major
obstacles of constructing a renormalizable non-commutative gauge field model
and sketch some possible ways out.Comment: 12 pages; v2: references adde
New Calabi-Yau Manifolds with Small Hodge Numbers

It is known that many Calabi-Yau manifolds form a connected web. The question
of whether all Calabi-Yau manifolds form a single web depends on the degree of
singularity that is permitted for the varieties that connect the distinct
families of smooth manifolds. If only conifolds are allowed then, since
shrinking two-spheres and three-spheres to points cannot affect the fundamental
group, manifolds with different fundamental groups will form disconnected webs.
We examine these webs for the tip of the distribution of Calabi-Yau manifolds
where the Hodge numbers (h^{11}, h^{21}) are both small. In the tip of the
distribution the quotient manifolds play an important role. We generate via
conifold transitions from these quotients a number of new manifolds. These
include a manifold with \chi =-6 and manifolds with an attractive structure
that may prove of interest for string phenomenology. We also examine the
relation of some of these manifolds to the remarkable Gross-Popescu manifolds
that have Euler number zero.Comment: 105 pages, pdflatex with about 70 pdf and jpeg figures. References
  corrected. Minor revisions to Fig1, and Table 9 extended to the range h^{11}
  + h^21 \leq 2
A Three-Generation Calabi-Yau Manifold with Small Hodge Numbers

We present a complete intersection Calabi-Yau manifold Y that has Euler
number -72 and which admits free actions by two groups of automorphisms of
order 12. These are the cyclic group Z_12 and the non-Abelian dicyclic group
Dic_3. The quotient manifolds have chi=-6 and Hodge numbers (h^11,h^21)=(1,4).
With the standard embedding of the spin connection in the gauge group, Y gives
rise to an E_6 gauge theory with 3 chiral generations of particles. The gauge
group may be broken further by means of the Hosotani mechanism combined with
continuous deformation of the background gauge field. For the non-Abelian
quotient we obtain a model with 3 generations with the gauge group broken to
that of the standard model. Moreover there is a limit in which the quotients
develop 3 conifold points. These singularities may be resolved simultaneously
to give another manifold with (h^11,h^21)=(2,2) that lies right at the tip of
the distribution of Calabi-Yau manifolds. This strongly suggests that there is
a heterotic vacuum for this manifold that derives from the 3 generation model
on the quotient of Y. The manifold Y may also be realised as a hypersurface in
the toric variety. The symmetry group does not act torically, nevertheless we
are able to identify the mirror of the quotient manifold by adapting the
construction of Batyrev.Comment: PDFLaTeX. 50 pages, 9 figures, 7 table
Optimal electron propagation on a quantum chain by a topological phase

8 pages, 6 figures.-- Published in Fortschritte der Physik 57(11-12): 1094-1102 (2009).-- http://dx.doi.org/10.1002/prop.200990010We study the quantum diffusion of an electron in a quantum chain starting from an initial state localized around a given site. As the wavepacket diffuses, the probability of reconstructing the initial state on another site diminishes drastically with the distance. In order to optimize the state transmission we find that a topological quantum phase can be introduced. The effect of this phase is the reduction of wavepacket spreading together with almost coherent group propagation. In this regime, the electron has a quasi-linear dispersion and high fidelity can be achieved also over large distances in terms of lattice spacing.The authors wish to acknowledge EU IP SCALA and Spanish MEC grant FIS 2008-/01236 QUICSUAP. GLG\ud
acknowledges the Juan de la Cierva fellowship of the Spanish Ministry of Education.Peer reviewe
Flavour Physics in the Littlest Higgs Model with T-Parity: Effects in
  the K, B_d/s and D systems

The Littlest Higgs Model with T parity (LHT) is an interesting alternative
model for New Physics at the TeV scale. Although Flavour Physics was not the
reason for creating the LHT model, significant effects (such as large CP
violation where not predicted by the SM) can be created without violating
existing experimental bounds. We study the B-, K- and especially the D-sector.Comment: Talk given at the Flavianet Workshop on Low energy constraints on
  extensions of the Standard Model, 23-27 July 2009, Kazimierz, Polan
Tracking Quintessence, WIMP Relic Density, PAMELA and Fermi LAT

The generation of an early kination dominated era within a tracking
quintessential model is investigated, the relic density of the Weakly
Interacting Massive Particles (WIMPs) is calculated and we show that it can be
enhanced with respect to its value in the standard cosmology. By adjusting the
parameters of the quintessential scenario, the cold dark matter abundance in
the universe can become compatible with large values for the annihilation cross
section times the velocity of the WIMPs. Using these values and assuming that
the WIMPs annihilate predominantly to $\mu^+\mu^-$, we calculate the induced
fluxes of $e^\pm$ cosmic rays and fit the current PAMELA and Fermi-LAT data. We
achieve rather good fits in conjunction with a marginal fulfillment of the
restriction arisen from the cosmic microwave background radiation.Comment: To appear in the proceedings of 9th Hellenic School and Workshops on
  Elementary Particle Physics and Gravity, Corfu (Greece) August 30 - September
  20, 200
Black Holes and Large N Species Solution to the Hierarchy Problem

We provide the perturbative and non-perturbative arguments showing that
theories with large number of species of the quantum fields, imply an
inevitable hierarchy between the masses of the species and the Planck scale,
shedding a different light on the hierarchy problem. In particular, using the
black hole physics, we prove that any consistent theory that includes N number
of the Z_2-conserved species of the quantum fields of mass \Lambda, puts a
lower bound on the Planck mass, which in large N limit is given by N\Lambda^2.
An useful byproduct of this proof is that any exactly conserved quantum charge,
not associated with a long-range classical field, must be defined maximum
modulo N, bounded by the the ratio of the Planck to the unit charge masses
squared. For example, a continuous global U(1) `baryon number' symmetry, must
be explicitly broken by gravity, at least down to a Z_N subgroup, with N
bounded by the ratio of the Planck to baryon masses squared. The same
constraint applies to any discrete gauge symmetry, as well as to other
quantum-mechanically detectable black hole charges that are associated with the
massive quantum hair of the black hole. We show that the
gravitationally-coupled N-species sector that solves the gauge hirearchy
problem, should be probed by LHC.Comment: 13 pages, Late
Asymptotic Helicity Conservation in SUSY

We summarize the extensive work started in ref.1, according to which total
helicity is conserved for any two-to-two process, at sqrt{s} larger than
M_{SUSY} and fixed angles, in any SUSY extension of SM. Asymptotically the
theorem is exact. But it may also have important implications at lower energies
sqrt{s} close to M_{SUSY}. Up to now, these have been investigated to 1loop
electroweak (EW) order for the processes ug to d W+, sd_L chi+; as well as the
17 gg to HH', and the 9 gg to VH processes, where H,H' denote Higgs or
Goldstone bosons, and V=Z, W.Comment: 4 pages, 2 figures,Talk presented by GJG at the meeting on the
  "Standard Model and beyond and the Standard Cosmology", held at Corfu
  (Greece), during August 30 - September 6, 200
On the fermion spectrum of spontaneously generated fuzzy extra
  dimensions with fluxes

We consider certain vacua of four-dimensional SU(N) gauge theory with the
same field content as the N=4 supersymmetric Yang-Mills theory, resulting from
potentials which break the N=4 supersymmetry as well as its global SO(6)
symmetry down to SO(3) x SO(3). We show that the theory behaves at intermediate
scales as Yang-Mills theory on M^4 x S^2 x S^2, where the extra dimensions are
fuzzy spheres with magnetic fluxes. We determine in particular the structure of
the zero modes due to the fluxes, which leads to low-energy mirror models.Comment: 18 pages, minor changes, references adde
Electroweak corrections to WWZ and ZZZ production at the linear collider

We calculate the electroweak corrections to the production of WWZ and ZZZ at
the linear collider in the Standard Model. These processes are important for
the extraction of the quartic couplings of the massive gauge bosons which can
be a window on the mechanism of spontaneous symmetry breaking. We find that the
weak corrections to some kinematic distributions show new features and hence
cannot be explained by an overall scale factor.Comment: 5 pages, 2 figs, contribution to the Corfu 2009 proceeding
Nearly-Kaehler dimensional reduction of the heterotic string

The effective action in four dimensions resulting from the ten-dimensional
N=1 heterotic supergravity coupled to N=1 supersymmetric Yang-Mills upon
dimensional reduction over nearly-Kaehler manifolds is discussed.
Nearly-Kaehler manifolds are an interesting class of manifolds admitting an
SU(3)-structure and in six dimensions all homogeneous nearly-Kaehler manifolds
are included in the class of the corresponding non-symmetric coset spaces plus
a group manifold. Therefore it is natural to apply the Coset Space Dimensional
Reduction scheme using these coset spaces as internal manifolds in order to
determine the four-dimensional theory.Comment: 11 pages, based on talk given at the Workshop on Cosmology-Strings,
  6-13 September 2009, second week of the 9th Hellenic School and Workshops on
  Elementary Particle Physics and Gravity, Corfu, Greec
Introduction to Superstring Cosmology

This is a summary of lectures in superstring cosmology given by the author at
the CORFU 2009 School and Workshops "Theory - Cosmology - Phenomenology", Corfu
Institute, Greece, Sept 6-13, 2009. These lectures are based on some recent
developments and ideas, in the framework of superstring theory, concerning the
evolution and structure of the universe in (i) the very early "non-geometric"'
cosmological era, (ii) the intermediate "radiation-like" era and (iii) the late
time cosmological era characterized by the electroweak phase transition.Comment: Summary of lectures in superstring cosmology given by the author at
  the CORFU 2009 School and Workshops "Theory - Cosmology - Phenomenology". 6
  page
NS5-branes, holography and CFT deformations

A few supergravity solutions representing configurations of NS5-branes admit
exact conformal field theory (CFT) description. Deformations of these solutions
should be described by exactly marginal operators of the corresponding
theories. We briefly review the essentials of these constructions and present,
as a new case, the operators responsible for turning on angular momentum.Comment: 6 pages, 2 figures, Proceedings contribution to the 9th Hellenic
  School on Elementary Particle Physics and Gravity}, Corfu, Greece, September
  200
Probing CP Violation with Kinematic Reconstruction at the LHC

We discuss the potential of observing effects of CP-violation phases in
squark decay chains at the LHC. As the CP-odd observable, we use the asymmetry
composed by triple products of final state momenta. There are good prospects of
observing these effects using the method of kinematic reconstruction for the
final and intermediate state particles. We also discuss the main experimental
factors and the expected sensitivity.Comment: 5 pages, 5 figures, submitted to the proceedings of the 9th Hellenic
  School on Elementary Particle Physics and Gravity, Corfu 200
An involuted orbifold MSSM

A compactification of the E_8 x E_8 heterotic string on a Z_2 x Z_2 orbifold
equipped with an additional freely acting involution is presented. This model
reproduces the exact chiral MSSM spectrum with matter parity and a non-trivial
Yukawa structure. The key ingredient is a freely acting Wilson line associated
to the involution, breaking SU(5) to SU(3) x SU(2) x U(1)_Y. This work is based
on a talk given at the "9th Hellenic School and Workshop on Elementary Particle
Physics and Gravity" and reviews the results of a collaboration with M.
Blaszczyk, S. Groot Nibbelink, M. Ratz, F. Ruehle and M. Trapletti.Comment: To appear in the proceedings of 9th Hellenic School and Workshops on
  Elementary Particle Physics and Gravity (CORFU 2009), Corfu, Greece, 30 Aug -
  20 Sep 2009
The "landscape" of Pati--Salam heterotic superstring vacua

The main aspects of a recently developed method for classification of
heterotic superstring vacua in the Free Fermionic Formulation are presented.
Using these techniques we classify a big number of approximately $10^{15}$
heterotic string vacua with Pati--Salam, SU(4)x{SU(2)}_Lx{SU(2)}_R gauge
symmetry with respect to their main phenomenological features as the number of
families, Pati--Salam breaking Higgs, Standard Model Higgs doublets, additional
triplets and exotic charge states. We identify an interesting subclass of these
vacua, approximately one to one million, whose massless spectrum is completely
free of fractionally charge states.Comment: 4 pages, 2 figues, Presented at "School and Workshops on Cosmology
  and Strings: Theory-Cosmology-Phenomenology" (CORFU2009), September 6-13,
  Corfu, Greec
On Classical de Sitter Vacua in String Theory

We review the prospect of obtaining tree-level de Sitter (dS) vacua and
slow-roll inflation models in string compactifications. Restricting ourselves
to the closed string sector and assuming the absence of NSNS-sources, we
classify the minimal classical ingredients that evade the simplest no-go
theorems against dS vacua and inflation. Spaces with negative integrated
curvature together with certain combinations of low-dimensional orientifold
planes and low-rank RR-fluxes emerge as the most promising setups of this
analysis. We focus on two well-controlled classes that lead to an effective 4D,
N=1 supergravity description: Type IIA theory on group or coset manifolds with
SU(3)-structure and O6-planes, as well as type IIB compactifications on
SU(2)-structure manifolds with O5- and O7-planes. While fully stabilized AdS
vacua are generically possible, a number of problems encountered in the search
for dS vacua are discussed.Comment: 4 pages, proceedings of the 9th Hellenic School on Elementary
  Particle Physics and Gravity, Corfu 200
The Electroweak Symmetry Breaking Riddle

I present a concise review of the Higgs problem which plays a central role in
particle physics today. The Higgs of the minimal Standard Model is so far just
a conjecture that needs to be verified or discarded at the LHC. Probably the
reality is more complicated. I will summarize the motivation for New Physics
that should accompany or even replace the Higgs discovery and a number of its
possible forms that could be revealed by the LHCComment: 17 pages, 3 figures, Talk presented at the Corfu Summer Institute:
  School and Workshop on the Standard Model and Beyond - Standard Cosmology,
  Corfu, Greece, August 31 - September 6, 2009 A few references added