13,641 research outputs found
BPS states in (2,0) theory on R x T5
We consider theory on a space-time of the form , where
the first factor denotes time, and the second factor is a flat spatial
five-torus. In addition to their energy, quantum states are characterized by
their spatial momentum, 't Hooft flux, and -symmetry
representation. The momentum obeys a shifted quantization law determined by the
't Hooft flux. By supersymmetry, the energy is bounded from below by the
magnitude of the momentum. This bound is saturated by BPS states, that are
annihilated by half of the supercharges. The spectrum of such states is
invariant under smooth deformations of the theory, and can thus be studied by
exploiting the interpretation of theory as an ultra-violet completion
of maximally supersymmetric Yang-Mills theory on . Our main
example is the -series of theories, where such methods allow us to
study the spectrum of BPS states for many values of the momentum and the 't
Hooft flux. In particular, we can describe the -symmetry transformation
properties of these states by determining the image of their
representation in a certain quotient of the representation ring.Comment: 22 page
Schwarzschild-anti de Sitter within an Isothermal Cavity: Thermodynamics, Phase Transitions and the Dirichlet Problem
The thermodynamics of Schwarzschild black holes within an isothermal cavity
and the associated Euclidean Dirichlet boundary-value problem are studied for
four and higher dimensions in anti-de Sitter (AdS) space. For such boundary
conditions classically there always exists a unique hot AdS solution and two or
no Schwarzschild-AdS black-hole solutions depending on whether or not the
temperature of the cavity-wall is above a minimum value, the latter being a
function of the radius of the cavity. Assuming the standard area-law of
black-hole entropy, it was known that larger and smaller holes have positive
and negative specific heats and hence are locally thermodynamically stable and
unstable respectively. In this paper we present the first derivation of this by
showing that the standard area law of black-hole entropy holds in the
semi-classical approximation of the Euclidean path integral for such boundary
conditions. We further show that for wall-temperatures above a critical value a
phase transition takes hot AdS to the larger Schwarzschild-AdS within the
cavity. The larger hole thus can be globally thermodynamically stable above
this temperature. The phase transition can occur for a cavity of arbitrary
radius above a (corresponding) critical temperature. In the infinite cavity
limit this picture reduces to that considered by Hawking and Page. The case of
five dimensions is found to be rather special since exact analytic expressions
can be obtained for the masses of the two holes as functions of cavity radius
and temperature thus solving exactly the Euclidean Dirichlet problem. This
makes it possible to compute the on-shell Euclidean action as functions of them
from which other quantities of interest can be evaluated exactly.Comment: 23 pages, Late
A Relation Between Gravity in --Dimensions and Pontrjagin Topological Invariant
A relation between the MacDowell-Mansouri theory of gravity and the
Pontrjagin toplogical invariant in dimensions is discussed. This
relation may be of especial interest in the quest of finding a mechanism to go
from non-dynamical to dynamical gravity.Comment: 9 pages, Te
Observations on the Topological Structure in 2d Gravity Coupled to Minimal Matter
By using a bosonization we uncover the topological gravity structure of
Labastida, Pernici and Witten in ordinary gravity coupled to
minimal models. We study the cohomology class associated with the fermionic
charge of the topological gravity which is shown to be isomorphic to that of
the total charge. One of the ground ring generators of string
theory is found to be in the equivariant cohomology of this fermionic charge.Comment: 13 pages, plain tex, UG-5/94 Some clarifying statements and two new
references adde
The quantum Hilbert space of a chiral two-form in d = 5 + 1 dimensions
We consider the quantum theory of a two-form gauge field on a space-time
which is a direct product of time and a spatial manifold, taken to be a compact
five-manifold with no torsion in its cohomology. We show that the Hilbert space
of this non-chiral theory is a certain subspace of a tensor product of two
spaces, that are naturally interpreted as the Hilbert spaces of a chiral and
anti-chiral two-form theory respectively. We also study the observable
operators in the non-chiral theory that correspond to the electric and magnetic
field strengths, the Hamiltonian, and the exponentiated holonomy of the
gauge-field around a spatial two-cycle. All these operators can be decomposed
into contributions pertaining to the chiral and anti-chiral sectors of the
theory.Comment: 15 page
A Holographic Prediction of the Deconfinement Temperature
We argue that deconfinement in AdS/QCD models occurs via a first order
Hawking-Page type phase transition between a low temperature thermal AdS space
and a high temperature black hole. Such a result is consistent with the
expected temperature independence, to leading order in 1/N_c, of the meson
spectrum and spatial Wilson loops below the deconfinement temperature. As a
byproduct, we obtain model dependent deconfinement temperatures T_c in the hard
and soft wall models of AdS/QCD. Our result for T_c in the soft wall model is
close to a recent lattice prediction.Comment: 4 pages, 1 figure; v2 ref added, minor changes; v3 refs added,
discussion modified, to appear in PR
Wilson-t'Hooft Loops in Finite-Temperature Non-commutative Dipole Field Theory from Dual Supergravity
We first study the temporal Wilson loop in the finite-temperature
non-commutative dipole field theory from the string/gauge correspondence. The
associated dual supergravity background is constructed from the near-horizon
geometry of near-extremal D-branes, after applying T-duality and smeared twist.
We investigate the string configuration therein and find that while the
temperature produces a maximum distance in the interquark distance
the dipole in there could produce a minimum distance . The quark
boundary pair therefore could be found only if their distance is between
and . We also show that, beyond a critical temperature the
quark pair becomes totally free due to screening by thermal bath. We next study
the spatial Wilson loop and find the confining nature in the zero temperature
3D and 4D non-supersymmetry dipole gauge theory. The string tension of the
linear confinement potential is obtained and found to be a decreasing function
of the dipole field. We also investigate the associated t'Hooft loop and
determine the corresponding monopole anti-monopole potential. The conventional
screening of magnetic charge which indicates the confinement of the electric
charge is replaced by a strong repulsive however. Finally, we show that the
dual string which is rotating along the dipole deformed will behave as a
static one without dipole field, which has no minimum distance and has larger
energy than a static one with dipole field. We discuss the phase transition
between these string solutions.Comment: Latex, 22 pages, 8 figures, add several comment
Holographic Derivation of Entanglement Entropy from AdS/CFT
A holographic derivation of the entanglement entropy in quantum (conformal)
field theories is proposed from AdS/CFT correspondence. We argue that the
entanglement entropy in d+1 dimensional conformal field theories can be
obtained from the area of d dimensional minimal surfaces in AdS_{d+2},
analogous to the Bekenstein-Hawking formula for black hole entropy. We show
that our proposal perfectly reproduces the correct entanglement entropy in 2D
CFT when applied to AdS_3. We also compare the entropy computed in AdS_5 \times
S^5 with that of the free N=4 super Yang-Mills.Comment: 5 pages, 3 figures, Revtex, references adde
Holographic Duals of Long Open Strings
We study the holographic map between long open strings, which stretch between
D-branes separated in the bulk space-time, and operators in the dual boundary
theory. We focus on a generalization of the Sakai-Sugimoto holographic model of
QCD, where the simplest chiral condensate involves an operator of this type.
Its expectation value is dominated by a semi-classical string worldsheet, as
for Wilson loops. We also discuss the deformation of the model by this
operator, and in particular its effect on the meson spectrum. This deformation
can be thought of as a generalization of a quark mass term to strong coupling.
It leads to the first top-down holographic model of QCD with a non-Abelian
chiral symmetry which is both spontaneously and explicitly broken, as in QCD.
Other examples we study include half-supersymmetric open Wilson lines, and
systems of D-branes ending on NS5-branes, which can be analyzed using
worldsheet methods.Comment: 35 pages, 4 figures, harvmac. v2: added reference
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