323 research outputs found
Loop expansion in Yang-Mills thermodynamics
We argue that a selfconsistent spatial coarse-graining, which involves
interacting (anti)calorons of unit topological charge modulus, implies that
real-time loop expansions of thermodynamical quantities in the deconfining
phase of SU(2) and SU(3) Yang-Mills thermodynamics are, modulo 1PI
resummations, determined by a finite number of connected bubble diagrams.Comment: 15 pages, 2 figures, v5: discussion of much more severely constrained
nonplanar situation included in Sec.
One Monopole with k Singularities
We present all charge one monopole solutions of the Bogomolny equation with k
prescribed Dirac singularities for the gauge groups U(2), SO(3), or SU(2). We
analyze these solutions comparing them to the previously known expressions for
the cases of one or two singularities.Comment: 12 pages, LaTe
Constraints on dark matter particles charged under a hidden gauge group from primordial black holes
In order to accommodate increasingly tighter observational constraints on
dark matter, several models have been proposed recently in which dark matter
particles are charged under some hidden gauge group. Hidden gauge charges are
invisible for the standard model particles, hence such scenarios are very
difficult to constrain directly. However black holes are sensitive to all gauge
charges, whether they belong to the standard model or not. Here, we examine the
constraints on the possible values of the dark matter particle mass and hidden
gauge charge from the evolution of primordial black holes. We find that the
existence of the primordial black holes with reasonable mass is incompatible
with dark matter particles whose charge to mass ratio is of the order of one.
For dark matter particles whose charge to mass ratio is much less than one, we
are able to exclude only heavy dark matter in the mass range of 10^(11) GeV -
10^(16) GeV. Finally, for dark matter particles whose charge to mass ratio is
much greater than one, there are no useful limits coming from primordial black
holes.Comment: accepted for publication in JCA
Rectangular Wilson Loops at Large N
This work is about pure Yang-Mills theory in four Euclidean dimensions with
gauge group SU(N). We study rectangular smeared Wilson loops on the lattice at
large N and relatively close to the large-N transition point in their
eigenvalue density. We show that the string tension can be extracted from these
loops but their dependence on shape differs from the asymptotic prediction of
effective string theory.Comment: 47 pages, 21 figures, 8 table
Diagonal deformations of thin center vortices and their stability in Yang-Mills theories
The importance of center vortices for the understanding of the confining
properties of SU(N) Yang-Mills theories is well established in the lattice.
However, in the continuum, there is a problem concerning the relevance of
center vortex backgrounds. They display the so called Savvidy-Nielsen-Olesen
instability, associated with a gyromagnetic ratio for the
off-diagonal gluons.
In this work, we initially consider the usual definition of a {\it thin}
center vortex and rewrite it in terms of a local color frame in SU(N)
Yang-Mills theories. Then, we define a thick center vortex as a diagonal
deformation of the thin object. Besides the usual thick background profile,
this deformation also contains a frame defect coupled with gyromagnetic ratio
, originated from the charged sector. As a consequence, the
analysis of stability is modified. In particular, we point out that the defect
should stabilize a vortex configuration formed by a pair of straight components
separated by an appropriate finite distance.Comment: 20 pages, LaTe
Holographic Phase Transition to Topological Dyons
The dynamical stability of a Julia-Zee solution in the AdS background in a
four dimensional Einstein-Yang-Mills-Higgs theory is studied. We find that the
model with a vanishing scalar field develops a non-zero value for the field at
a certain critical temperature which corresponds to a topological dyon in the
bulk and a topological phase transition at the boundary.Comment: 18 pages, 2 figures, 2 tables, sections 2 and 4 are shortened, an
error in the last part of section 5 is corrected and equations are modified.
This version to be published in JHE
Wilson loops stability in the gauge/string correspondence
We study the stability of some classical string worldsheet solutions employed
for computing the potential energy between two static fundamental quarks in
confining and non-confining gravity duals. We discuss the fixing of the
diffeomorphism invariance of the string action, its relation with the
fluctuation orientation and the interpretation of the quark mass substraction
worldsheet needed for computing the potential energy in smooth (confining)
gravity background. We consider various dual gravity backgrounds and show by a
numerical analysis the existence of instabilities under linear fluctuations for
classical string embedding solutions having positive length function derivative
. Finally we make a brief discussion of 't Hooft loops in
non-conformal backgrounds.Comment: 34 pages, 36 figures. Reference added. Final version JHEP accepte
The semi-classical expansion and resurgence in gauge theories: new perturbative, instanton, bion, and renormalon effects
We study the dynamics of four dimensional gauge theories with adjoint
fermions for all gauge groups, both in perturbation theory and
non-perturbatively, by using circle compactification with periodic boundary
conditions for the fermions. There are new gauge phenomena. We show that, to
all orders in perturbation theory, many gauge groups are Higgsed by the gauge
holonomy around the circle to a product of both abelian and nonabelian gauge
group factors. Non-perturbatively there are monopole-instantons with fermion
zero modes and two types of monopole-anti-monopole molecules, called bions. One
type are "magnetic bions" which carry net magnetic charge and induce a mass gap
for gauge fluctuations. Another type are "neutral bions" which are magnetically
neutral, and their understanding requires a generalization of multi-instanton
techniques in quantum mechanics - which we refer to as the
Bogomolny-Zinn-Justin (BZJ) prescription - to compactified field theory. The
BZJ prescription applied to bion-anti-bion topological molecules predicts a
singularity on the positive real axis of the Borel plane (i.e., a divergence
from summing large orders in peturbation theory) which is of order N times
closer to the origin than the leading 4-d BPST instanton-anti-instanton
singularity, where N is the rank of the gauge group. The position of the
bion--anti-bion singularity is thus qualitatively similar to that of the 4-d IR
renormalon singularity, and we conjecture that they are continuously related as
the compactification radius is changed. By making use of transseries and
Ecalle's resurgence theory we argue that a non-perturbative continuum
definition of a class of field theories which admit semi-classical expansions
may be possible.Comment: 112 pages, 7 figures; v2: typos corrected, discussion of
supersymmetric models added at the end of section 8.1, reference adde
Matrix Models for the Black Hole Information Paradox
We study various matrix models with a charge-charge interaction as toy models
of the gauge dual of the AdS black hole. These models show a continuous
spectrum and power-law decay of correlators at late time and infinite N,
implying information loss in this limit. At finite N, the spectrum is discrete
and correlators have recurrences, so there is no information loss. We study
these models by a variety of techniques, such as Feynman graph expansion, loop
equations, and sum over Young tableaux, and we obtain explicitly the leading
1/N^2 corrections for the spectrum and correlators. These techniques are
suggestive of possible dual bulk descriptions. At fixed order in 1/N^2 the
spectrum remains continuous and no recurrence occurs, so information loss
persists. However, the interchange of the long-time and large-N limits is
subtle and requires further study.Comment: 35 pages, 11 eps figures; v.2 minor typos fixe
Soliton pair creation in classical wave scattering
We study classical production of soliton-antisoliton pairs from colliding
wave packets in (1+1)-dimensional scalar field model. Wave packets represent
multiparticle states in quantum theory; we characterize them by energy E and
particle number N. Sampling stochastically over the forms of wave packets, we
find the entire region in (E,N) plane which corresponds to classical creation
of soliton pairs. Particle number is parametrically large within this region
meaning that the probability of soliton-antisoliton pair production in
few-particle collisions is exponentially suppressed.Comment: 16 pages, 8 figures, journal version; misprint correcte
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