7,513 research outputs found
Wu-Yang Monopoles and Non-Abelian Seiberg-Witten Equations
Some exact solutions of the SU(2) Seiberg-Witten equations in Minkowski
spacetime are given.Comment: 6 pages, LATEX file, no figures. To appear in Mod. Phys. Lett.
Gravitational Backreaction Effects on the Holographic Phase Transition
We study radion stabilization in the compact Randall-Sundrum model by
introducing a bulk scalar field, as in the Goldberger and Wise mechanism, but
(partially) taking into account the backreactions from the scalar field on the
metric. Our generalization reconciles the radion potential found by Goldberger
and Wise with the radion mass obtained with the so-called superpotential method
where backreaction is fully considered. Moreover we study the holographic phase
transition and its gravitational wave signals in this model. The improved
control over backreactions opens up a large region in parameter space and
leads, compared to former analysis, to weaker constraints on the rank N of the
dual gauge theory. We conclude that, in the regime where the 1/N expansion is
justified, the gravitational wave signal is detectable by LISA.Comment: 42 pages, 4 figures; v2: minor changes for the publicatio
Graviton n-point functions for UV-complete theories in Anti-de Sitter space
We calculate graviton n-point functions in an anti-de Sitter black brane
background for effective gravity theories whose linearized equations of motion
have at most two time derivatives. We compare the n-point functions in Einstein
gravity to those in theories whose leading correction is quadratic in the
Riemann tensor. The comparison is made for any number of gravitons and for all
physical graviton modes in a kinematic region for which the leading correction
can significantly modify the Einstein result. We find that the n-point
functions of Einstein gravity depend on at most a single angle, whereas those
of the corrected theories may depend on two angles. For the four-point
functions, Einstein gravity exhibits linear dependence on the Mandelstam
variable s versus a quadratic dependence on s for the corrected theory.Comment: 29 page
Evidence for fast thermalization in the plane-wave matrix model
We perform a numerical simulation of the classical evolution of the
plane-wave matrix model with semiclassical initial conditions. Some of these
initial conditions thermalize and are dual to a black hole forming from the
collision of D-branes in the plane wave geometry. In particular, we consider a
large fuzzy sphere (a D2-brane) plus a single eigenvalue (a D0-particle) going
exactly through the center of the fuzzy sphere and aimed to intersect it.
Including quantum fluctuations of the off-diagonal modes in the initial
conditions, with sufficient kinetic energy the configuration collapses to a
small size. We also find evidence for fast thermalization: rapidly decaying
autocorrelation functions at late times with respect to the natural time scale
of the system.Comment: 5 pages, 5 figures, revtex4 format; v2: minor typos fixed; v3: 8
pages, 9 figures, minor changes, includes a supplement as appeared on PR
Bound states in N = 4 SYM on T^3: Spin(2n) and the exceptional groups
The low energy spectrum of (3+1)-dimensional N=4 supersymmetric Yang-Mills
theory on a spatial three-torus contains a certain number of bound states,
characterized by their discrete abelian magnetic and electric 't Hooft fluxes.
At weak coupling, the wave-functions of these states are supported near points
in the moduli space of flat connections where the unbroken gauge group is
semi-simple. The number of such states is related to the number of normalizable
bound states at threshold in the supersymmetric matrix quantum mechanics with
16 supercharges based on this unbroken group. Mathematically, the determination
of the spectrum relies on the classification of almost commuting triples with
semi-simple centralizers. We complete the work begun in a previous paper, by
computing the spectrum of bound states in theories based on the
even-dimensional spin groups and the exceptional groups. The results satisfy
the constraints of S-duality in a rather non-trivial way.Comment: 20 page
D-instantons probing D3-branes and the AdS/CFT correspondence
D-instantons are considered as a probe of coinciding D3-branes. They can
feel an external metric via the commutator terms in their effective action. We
show that when the D-instantons are separated from the D3-branes, the metric
which is probed at the one loop level, {\it exactly} coincides with that of the
BPS R-R 3-brane. Interesting connection of this result to the possible
explanation of the AdS/CFT correspondence within IKKT M-atrix theory is
discussed.Comment: 8pp., Latex. Minor changes, misprints are correcte
Compressing nearly hard sphere fluids increases glass fragility
We use molecular dynamics to investigate the glass transition occurring at
large volume fraction, phi, and low temperature, T, in assemblies of soft
repulsive particles. We find that equilibrium dynamics in the (phi, T) plane
obey a form of dynamic scaling in the proximity of a critical point at T=0 and
phi=phi_0, which should correspond to the ideal glass transition of hard
spheres. This glass point, `point G', is distinct from athermal jamming
thresholds. A remarkable consequence of scaling behaviour is that the dynamics
at fixed phi passes smoothly from that of a strong glass to that of a very
fragile glass as phi increases beyond phi_0. Correlations between fragility and
various physical properties are explored.Comment: 5 pages, 3 figures; Version accepted at Europhys. Let
A class of six-dimensional conformal field theories
We describe a class of six-dimensional conformal field theories that have
some properties in common with and possibly are related to a subsector of the
tensionless string theories. The latter theories can for example give rise to
four-dimensional superconformal Yang-Mills theories upon
compactification on a two-torus. Just like the tensionless string theories, our
theories have an -classification, but no other discrete or continuous
parameters. The Hilbert space carries an irreducible representation of the same
Heisenberg group that appears in the tensionless string theories, and the
`Wilson surface' observables obey the same superselection rules. When
compactified on a two-torus, they have the same behaviour under -duality as
super Yang-Mills theory. Our theories are natural generalizations of the
two-form with self-dual field strength that is part of the world-volume theory
of a single five-brane in -theory, and the theory can in fact be
seen as arising from non-interacting chiral two-forms by factoring out the
collective `center of mass' degrees of freedom.Comment: 8 pages. More pedagogical presentation, added section on relationship
to d = 4 Yang-Mills theor
Spontaneous Z2 Symmetry Breaking in the Orbifold Daughter of N=1 Super Yang-Mills Theory, Fractional Domain Walls and Vacuum Structure
We discuss the fate of the Z2 symmetry and the vacuum structure in an
SU(N)xSU(N) gauge theory with one bifundamental Dirac fermion. This theory can
be obtained from SU(2N) supersymmetric Yang--Mills (SYM) theory by virtue of Z2
orbifolding. We analyze dynamics of domain walls and argue that the Z2 symmetry
is spontaneously broken. Since unbroken Z2 is a necessary condition for
nonperturbative planar equivalence we conclude that the orbifold daughter is
nonperturbatively nonequivalent to its supersymmetric parent. En route, our
investigation reveals the existence of fractional domain walls, similar to
fractional D-branes of string theory on orbifolds. We conjecture on the fate of
these domain walls in the true solution of the Z2-broken orbifold theory. We
also comment on relation with nonsupersymmetric string theories and
closed-string tachyon condensation.Comment: 37 pages, 7 figures. v2: various significant changes; revisions
explained in the introduction. Final version to appear in Phys.Rev.
Low Energy Skyrmion-Skyrmion Scattering
We study the scattering of Skyrmions at low energy and large separation using
the method proposed by Manton of truncation to a finite number of degrees
freedom. We calculate the induced metric on the manifold of the union of
gradient flow curves, which for large separation, to first non-trivial order is
parametrized by the variables of the product ansatz. (presented at the Lake
Louise Winter Institute, 1994)Comment: 6 page
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