arXiv subjects

P. Suranyi

Publications and source records attributed to P. Suranyi.

At least 19 recordsLinked to original sources

arXiv2011

Classical instability in Lovelock gravity

We introduce a simple method for the investigation of the classical stability of static solutions with a horizon in Lovelock gravity. The method is applicable to the investigation of high angular momentum instabilities, similar to those found by Dotti and Gleiser for Gauss-Bonnet black holes. The method does not require the knowledge of the explicit analytic form of the black hole solution. In this paper we apply our method to a case where the explicit solution is known and show that it identifies correctly the resulting unstable modes.

hep-th↗

arXiv2010

Do microscopic stable black holes contribute to dark matter?

We investigate some of the experimental, observational and theoretical consequences of hypothetical stable black holes in the mass range between the electro-weak scale and the Planck mass, 2.4$\times 10^{15}$ TeV. For the purpose of calculations we use Lovelock black holes in odd dimensions. If such black holes exist they contribute to dark matter. We show that the passage of the black holes through matter and the collision of black holes have a well defined experimental signature. Depending on their cross section and energy they also accumulate in stars and influence their development.

hep-ph↗

arXiv2009

The fate of black branes in Einstein-Gauss-Bonnet gravity

Black branes are studied in Einstein-Gauss-Bonnet (EGB) gravity. Evaporation drives black branes towards one of two singularities depending on the sign of $α$, the Gauss-Bonnet coupling. For positive $α$ and sufficiently large ratio $\sqrtα/L$, where $L/2π$ is the radius of compactification, black branes avoid the Gregory-Laflamme (GL) instability before reaching a critical state. No black branes with the radius of horizon smaller than the critical value can exist. Approaching the critical state branes have a nonzero Hawking temperature. For negative $α$ all black branes encounter the GL instability. No black branes may exist outside of the interval of the critical values, $0\leqβ<3$, where $β=1- 8α/r_h^2$ and $r_h$ is the radius of horizon of the black brane. The first order phase transition line of GL transitions ends in a second order phase transition point at $β=0$.

hep-th↗

arXiv2005

Thermodynamics of static black objects in D dimensional Einstein-Gauss-Bonnet gravity with D-4 compact dimensions

We investigate the thermodynamics of static black objects such as black holes, black strings and their generalizations to D dimensions (`black branes') in a gravitational theory containing the four dimensional Gauss-Bonnet term in the action, when D-4 of the dimensions are compactified on a torus. The entropies of black holes and black branes are compared to obtain information on the stability of these objects and to find their phase diagrams. We demonstrate the existence of a critical mass, which depends on the scale of the compactified dimensions, below which the black hole entropy dominates over the entropy of the black membrane.

gr-qc↗

arXiv2004

Analytic approximation to 5 dimensional Black Holes with one compact dimension

We study black hole solutions in $R^4\times S^1$ space, using an expansion to fourth order in the ratio of the radius of the horizon, $μ$, and the circumference of the compact dimension, $L$. A study of geometric and thermodynamic properties indicates that the black hole fills the space in the compact dimension at $ε(μ/L)^2\simeq0.1$. At the same value of $ε$ the entropies of the uniform black string and of the black hole are approximately equal.

hep-th↗

arXiv2004

Small Black Holes on Branes: Is the horizon regular or singular ?

We investigate the following question: Consider a small mass, with $ε$ (the ratio of the Schwarzschild radius and the bulk curvature length) much smaller than 1, that is confined to the TeV brane in the Randall-Sundrum I scenario. Does it form a black hole with a regular horizon, or a naked singularity? The metric is expanded in $ε$ and the asymptotic form of the metric is given by the weak field approximation (linear in the mass). In first order of $ε$ we show that the iteration of the weak field solution, which includes only integer powers of the mass, leads to a solution that has a singular horizon. We find a solution with a regular horizon but its asymptotic expansion in the mass also contains half integer powers.

gr-qc↗

arXiv2004

Small Black Holes in Randall-Sundrum type I Scenario

An approximation method to study the properties of a small black hole located on the TeV brane in the Randall-Sundrum type I scenario is presented. The method enables us to find the form of the metric close to the matter distribution when its asymptotic form is given. The short range solution is found as an expansion in the ratio between the Schwarzschild radius of the black hole and the curvature length of the bulk. Long range properties are introduced using the linearized gravity solution as an asymptotic boundary condition. The solution is found up to first order. It is valid in the region close to the horizon but is not valid on the horizon. The regularity of the horizon is still under study.

gr-qc↗

arXiv2002

Black Holes in brane worlds

In a Randall-Sundrum theory (RS1) 3+1 dimensional black holes and higher dimensional black holes are not the natural continuations of each other. 3+1 dimensional black holes decay into a large number of 4+1 dimensional black holes at a critical mass, $M_{\rm crit}\sim 10^{32}$ TeV. Those black holes themselves may become unstable above another, albeit much smaller critical mass, $M_0\sim 10^3$TeV.

hep-th↗

arXiv2001

Monopoles and vortices in pure gauge theories and in Higgs theories

Smeared Abelian and center gauges are introduced in pure non-Abelian lattice gauge theories. Popular Abelian and center gauges are limits of smeared gauges. Smeared gauges are also shown to be equivalent to Higgs theories. As a result, distributions and interactions of monopoles and vortices, which are objects responsible for confinement in pure gauge theories, can be studied by investigating classical solutions of Higgs theories.

hep-lat↗

arXiv2000

Curved, extended classical solutions I. The undulating kink

The energy of extended classical objects, such as vortices, depends on their shape. In particular, we show that the curvature energy of a kink in two spatial dimensions, as a prototype of extended classical solutions, is always negative. We obtain a closed form for the curvature energy, assuming small deviations from the straight line.

hep-th↗

arXiv2000

New vortex solution in SU(3) gauge-Higgs theory

Following a brief review of known vortex solutions in SU(N) gauge-adjoint Higgs theories we show the existence of a new ``minimal'' vortex solution in SU(3) gauge theory with two adjoint Higgs bosons. At a critical coupling the vortex decouples into two abelian vortices, satisfying Bogomol'nyi type, first order, field equations. The exact value of the vortex energy (per unit length) is found in terms of the topological charge that equals to the N=2 supersymmetric charge, at the critical coupling. The critical coupling signals the increase of the underlying supersymmetry.

hep-th↗

arXiv1998

Simulation of an Abelian Higgs theory in world line (polymer) representation

In World Line Path Integral representation Abelian Higgs theories admit a curvature term in the Hamiltonian. Using Monte Carlo simulations we show that the curvature term drives a phase transition at sufficiently strong coupling. In quenched approximation this phase transition is smooth, with implications that the model reduces to a Goldstone theory. Critical properties of the system near the transition are investigated and found to be consistent with mean field behavior.

hep-lat↗

arXiv1997

Solution of gauge theories induced by fundamental representation scalars

Gauge theories induced by scalars in the fundamental representation of the $U(N_c)_{gauge}\times U(N_f)_{global}$ group are investigated in the large $N_c$ and $N_f$ limit. A master field is defined from bilinears of the scalar field following an Eguchi-Kawai type reduction of spacetime. The density function for the master field satisfies an integral equation that can be solved exactly in two dimensions (D=2) and in a convergent series of approximations at $D>2$. While at D=2 the system is in the same phase at all $ε=N_c/N_f$, it undergoes a phase transition at a critical value, $ε_c(D)$, for $D>2$.

hep-ph↗

arXiv1996

Gauge theories induced by bosons in fundamental representation

A lattice theory of scalar bosons in the fundamental representation of the gauge group $SU(N_c)$ and of the global symmetry group $SU(N_f)$ is shown to induce a standard gauge theory only at large $N_f$. The system is in a deconfined phase at strong scalar self-coupling and any finite $N_f$. The requirement of convergence of the effective gauge action imposes a lower limit on the scalar mass.

hep-lat↗

arXiv1995

Gauged Yukawa Matrix Models and 2-Dimensional Lattice Theories

We argue that chiral symmetry breaking in three dimensional QCD can be identified with Néel order in 2-dimensional quantum antiferromagnets. When operators which drive the chiral transition are added to these theories, we postulate that the resulting quantum critical behavior is in the universality class of gauged Yukawa matrix models. As a consequence, the chiral transition is typically of first order, although for a limited class of parameters it can be second order with computable critical exponents.

hep-ph↗

arXiv1995

New Universality Classes for Quantum Critical Behavior

We use the epsilon expansion to explore a new universality class of second order quantum phase transitions associated with a four-dimensional Yukawa field theory coupled to a traceless Hermitean matrix scalar field. We argue that this class includes four-fermi models in $2<D<4$ dimensions with $SU(N_F)\times U(N)$ symmetry and a U(N) scalar, $SU(N_F)$ iso-vector 4-fermi coupling. The epsilon expansion indicates that there is a second order phase transition for $N\geq N^*(N_F)$, where $N^*(N_F)\simeq.27N_F$ if $N_F\to\infty$.

hep-ph↗

arXiv1995

Phase Transitions and Mass Generation in 2+1 Dimensions

The possibility that the epsilon expansion can predict the order of phase transitions in three dimensional field theories is examined. For a Hermitean matrix-valued order parameter, the epsilon expansion predicts fluctuation induced first order phase transitions. We analyze two 2+1-dimensional quantum field theories which exhibit spontaneous symmetry breaking and have martix order parameters. Using the large $N$ expansion, we show that these models exhibit second order transitions and discuss the implications for the chiral symmetry breaking transition in 2+1-dimensional QCD for a critical number of quark flavors.

hep-ph↗

arXiv1994

Duals of nonabelian gauge theories in $D$ dimensions

The dual of an arbitrary $D$-dimensional nonabelian lattice gauge theory, obtained after character expansion and integration over the gauge group, is shown to be a {\em local} lattice theory in the eigenspace of the Casimir operators. For $D\leq4$ we also provide the explicit form of the action as a product of character expansion coefficients and Racah coefficients. The representation can be used to facilitate strong coupling expansions. Furthermore, the possibility of simulations, at weak coupling, in the dual representation, is also discussed.

hep-lat↗