79 research outputs found
Uniqueness of the asymptotic AdS3 geometry
We explicitly show that in (2+1) dimensions the general solution of the
Einstein equations with negative cosmological constant on a neigbourhood of
timelike spatial infinity can be obtained from BTZ metrics by coordinate
transformations corresponding geometrically to deformations of their spatial
infinity surface. Thus, whatever the topology and geometry of the bulk, the
metric on the timelike extremities is BTZ.Comment: LaTeX, 8 pages, no figures, version that will appear in Class. Quant.
Gra
Branes, Orientifolds and the Creation of Elementary Strings
The potential of a configuration of two Dirichlet branes for which the number
of ND-directions is eight is determined. Depending on whether one of the branes
is an anti-brane or a brane, the potential vanishes or is twice as large as the
dilaton-gravitational potential. This is shown to be related to the fact that a
fundamental string is created when two such branes cross. Special emphasis is
given to the D0-D8 system, for which an interpretation of these results in
terms of the massive IIA supergravity is presented. It is also shown that the
branes cannot move non-adiabatically in the transverse direction. The
configuration of a zero brane and an orientifold 8-plane is analyzed in a
similar way, and some implications for the type IA-heterotic duality and the
heterotic matrix theory are discussed.Comment: 24 pages, LaTeX, 4 postscript-figures; substantial changes to
sections 2 and
Diffeomorphisms and Holographic Anomalies
Using the relation between diffeomorphisms in the bulk and Weyl
transformations on the boundary we study the Weyl transformation properties of
the bulk metric on shell and of the boundary action. We obtain a universal
formula for one of the classes of trace anomalies in any even dimension in
terms of the parameters of the gravity action.Comment: 12 pages, harvma
Black holes with topologically nontrivial AdS asymptotics
Asymptotically locally AdS black hole geometries of dimension d > 2 are
studied for nontrivial topologies of the transverse section. These geometries
are static solutions of a set of theories labeled by an integer 0 < k <
[(d-1)/2] which possess a unique globally AdS vacuum. The transverse sections
of these solutions are d-2 surfaces of constant curvature, allowing for
different topological configurations. The thermodynamic analysis of these
solutions reveals that the presence of a negative cosmological constant is
essential to ensure the existence of stable equilibrium states. In addition, it
is shown that these theories are holographically related to [(d-1)/2] different
conformal field theories at the boundary.Comment: 13 Pages, 3 figures, two columns, Revtex, last version for PR
Black Hole Scan
Gravitation theories selected by requiring that they have a unique anti-de
Sitter vacuum with a fixed cosmological constant are studied. For a given
dimension d, the Lagrangians under consideration are labeled by an integer
k=1,2,...,[(d-1)/2]. Black holes for each d and k are found and are used to
rank these theories. A minimum possible size for a localized electrically
charged source is predicted in the whole set of theories, except General
Relativity. It is found that the thermodynamic behavior falls into two classes:
If d-2k=1, these solutions resemble the three dimensional black hole,
otherwise, their behavior is similar to the Schwarzschild-AdS_4 geometry.Comment: Two columns, revtex, 15 pages, 5 figures, minor typos corrected,
final version for Journa
Massive type IIA string theory cannot be strongly coupled
Understanding the strong coupling limit of massive type IIA string theory is
a longstanding problem. We argue that perhaps this problem does not exist;
namely, there may be no strongly coupled solutions of the massive theory. We
show explicitly that massive type IIA string theory can never be strongly
coupled in a weakly curved region of space-time. We illustrate our general
claim with two classes of massive solutions in AdS4xCP3: one, previously known,
with N = 1 supersymmetry, and a new one with N = 2 supersymmetry. Both
solutions are dual to d = 3 Chern-Simons-matter theories. In both these massive
examples, as the rank N of the gauge group is increased, the dilaton initially
increases in the same way as in the corresponding massless case; before it can
reach the M-theory regime, however, it enters a second regime, in which the
dilaton decreases even as N increases. In the N = 2 case, we find
supersymmetry-preserving gauge-invariant monopole operators whose mass is
independent of N. This predicts the existence of branes which stay light even
when the dilaton decreases. We show that, on the gravity side, these states
originate from D2-D0 bound states wrapping the vanishing two-cycle of a
conifold singularity that develops at large N.Comment: 43 pages, 5 figures. v2: added reference
M-Theory as a Holographic Field Theory
We suggest that M-theory could be non-perturbatively equivalent to a local
quantum field theory. More precisely, we present a ``renormalizable'' gauge
theory in eleven dimensions, and show that it exhibits various properties
expected of quantum M-theory, most notably the holographic principle of
't~Hooft and Susskind. The theory also satisfies Mach's principle: A
macroscopically large space-time (and the inertia of low-energy excitations) is
generated by a large number of ``partons'' in the microscopic theory. We argue
that at low energies in large eleven dimensions, the theory should be
effectively described by eleven-dimensional supergravity. This effective
description breaks down at much lower energies than naively expected, precisely
when the system saturates the Bekenstein bound on energy density. We show that
the number of partons scales like the area of the surface surrounding the
system, and discuss how this holographic reduction of degrees of freedom
affects the cosmological constant problem. We propose the holographic field
theory as a candidate for a covariant, non-perturbative formulation of quantum
M-theory.Comment: 27 pp. v2: typos corrected; a small paragraph on naturalness of small
cosmological constant in four dimensions added at end of sect 5.1; final
version to appear in Phys. Rev.
Holography and the Polyakov action
In two dimensional conformal field theory the generating functional for
correlators of the stress-energy tensor is given by the non-local Polyakov
action associated with the background geometry. We study this functional
holographically by calculating the regularized on-shell action of
asymptotically AdS gravity in three dimensions, associated with a specified
(but arbitrary) boundary metric. This procedure is simplified by making use of
the Chern-Simons formulation, and a corresponding first-order expansion of the
bulk dreibein, rather than the metric expansion of Fefferman and Graham. The
dependence of the resulting functional on local moduli of the boundary metric
agrees precisely with the Polyakov action, in accord with the AdS/CFT
correspondence. We also verify the consistency of this result with regard to
the nontrivial transformation properties of bulk solutions under Brown-Henneaux
diffeomorphisms.Comment: 20 pages, RevTeX, v2: minor typos corrected and references adde
Categorizing Different Approaches to the Cosmological Constant Problem
We have found that proposals addressing the old cosmological constant problem
come in various categories. The aim of this paper is to identify as many
different, credible mechanisms as possible and to provide them with a code for
future reference. We find that they all can be classified into five different
schemes of which we indicate the advantages and drawbacks.
Besides, we add a new approach based on a symmetry principle mapping real to
imaginary spacetime.Comment: updated version, accepted for publicatio
Quantum Gravity in 2+1 Dimensions: The Case of a Closed Universe
In three spacetime dimensions, general relativity drastically simplifies,
becoming a ``topological'' theory with no propagating local degrees of freedom.
Nevertheless, many of the difficult conceptual problems of quantizing gravity
are still present. In this review, I summarize the rather large body of work
that has gone towards quantizing (2+1)-dimensional vacuum gravity in the
setting of a spatially closed universe.Comment: 61 pages, draft of review for Living Reviews; comments, criticisms,
additions, missing references welcome; v2: minor changes, added reference
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