505 research outputs found
Quantum effective action from the AdS/CFT correspondence
We obtain an Einstein metric of constant negative curvature given an
arbitrary boundary metric in three dimensions, and a conformally flat one given
an arbitrary conformally flat boundary metric in other dimensions. In order to
compute the on-shell value of the gravitational action for these solutions, we
propose to integrate the radial coordinate from the boundary till a critical
value where the bulk volume element vanishes. The result, which is a functional
of the boundary metric, provides a sector of the quantum effective action
common to all conformal field theories that have a gravitational description.
We verify that the so-defined boundary effective action is conformally
invariant in odd (boundary) dimensions and has the correct conformal anomaly in
even (boundary) dimensions. In three dimensions and for arbitrary static
boundary metric the bulk metric takes a rather simple form. We explicitly carry
out the computation of the corresponding effective action and find that it
equals the non-local Polyakov action.Comment: 12 pages, latex, no figures; v2: minor improvements and two
references adde
Branes in the plane wave background with gauge field condensates
Supersymmetric branes in the plane wave background with additional constant
magnetic fields are studied from the world-sheet point of view. It is found
that in contradistinction to flat space, boundary condensates on some maximally
supersymmetric branes necessarily break at least some supersymmetries. The
maximally supersymmetric cases with condensates are shown to be in one to one
correspondence with the previously classified class II branes.Comment: LaTeX, 31 pages, no figures; v2: references added, some typos
correcte
The Holographic Universe
We present a holographic description of four-dimensional single-scalar
inflationary universes in terms of a three-dimensional quantum field theory.
The holographic description correctly reproduces standard inflationary
predictions in their regime of applicability. In the opposite case, wherein
gravity is strongly coupled at early times, we propose a holographic
description in terms of perturbative QFT and present models capable of
satisfying the current observational constraints while exhibiting a
phenomenology distinct from standard inflation. This provides a qualitatively
new method for generating a nearly scale-invariant spectrum of primordial
cosmological perturbations.Comment: 20 pages, 5 figs; extended version of arXiv:0907.5542 including
background material and detailed derivations. To appear in Proceedings of 1st
Mediterranean Conference on Classical and Quantum Gravit
Gravity in Warped Compactifications and the Holographic Stress Tensor
We study gravitational aspects of Brane-World scenarios. We show that the bulk Einstein equations together with the junction condition imply that the induced metric on the brane satisfies the full non-linear Einstein equations with a specific effective stress energy tensor. This result holds for any value of the bulk cosmological constant. The analysis is done by either placing the brane close to infinity or by considering the local geometry near the brane. In the case that the bulk spacetime is asymptotically AdS, we show that the effective stress energy tensor is equal to the sum of the stress energy tensor of matter localized on the brane and of the holographic stress energy tensor appearing in the AdS/CFT duality. In addition, there are specific higher-curvature corrections to Einstein's equations. We analyze in detail the case of asymptotically flat spacetime. We obtain asymptotic solutions of Einstein's equations and show that the effective Newton's constant on the brane depends on the position of the brane
Supersymmetric hydrodynamics from the AdS/CFT correspondence
We compute holographically the dispersion relation for a hydrodynamic mode of
fluctuation (the phonino) of the density of supersymmetry current in N = 4 SYM
at strong coupling. The mode appears as a pole at low frequency and momentum in
the correlator of supercurrents. It has a wave-like propagation, and we find
its speed and coefficient of attenuation.Comment: 17 page
Kaluza-Klein Holography
We construct a holographic map between asymptotically AdS_5 x S^5 solutions
of 10d supergravity and vacuum expectation values of gauge invariant operators
of the dual QFT. The ingredients that enter in the construction are (i) gauge
invariant variables so that the KK reduction is independent of any choice of
gauge fixing; (ii) the non-linear KK reduction map from 10 to 5 dimensions
(constructed perturbatively in the number of fields); (iii) application of
holographic renormalization. A non-trivial role in the last step is played by
extremal couplings. This map allows one to reliably compute vevs of operators
dual to any KK fields. As an application we consider a Coulomb branch solution
and compute the first two non-trivial vevs, involving operators of dimension 2
and 4, and reproduce the field theory result, in agreement with
non-renormalization theorems. This constitutes the first quantitative test of
the gravity/gauge theory duality away from the conformal point involving a vev
of an operator dual to a KK field (which is not one of the gauged supergravity
fields).Comment: 47 pages, v2: minor improvements, version to appear in JHE
The volume of causal diamonds, asymptotically de Sitter space-times and irreversibility
In this note we prove that the volume of a causal diamond associated with an
inertial observer in asymptotically de Sitter 4-dimensional space-time is
monotonically increasing function of cosmological time. The asymptotic value of
the volume is that of in maximally symmetric de Sitter space-time. The
monotonic property of the volume is checked in two cases: in vacuum and in the
presence of a massless scalar field. In vacuum, the volume flow (with respect
to cosmological time) asymptotically vanishes if and only if future space-like
infinity is 3-manifold of constant curvature. The volume flow thus represents
irreversibility of asymptotic evolution in spacetimes with positive
cosmological constant.Comment: 15 pages, no figures; v.2: conjecture 1 on p. 11 made more precise;
version published in jhe
Anatomy of bubbling solutions
We present a comprehensive analysis of holography for the bubbling solutions
of Lin-Lunin-Maldacena. These solutions are uniquely determined by a coloring
of a 2-plane, which was argued to correspond to the phase space of free
fermions. We show that in general this phase space distribution does not
determine fully the 1/2 BPS state of N=4 SYM that the gravitational solution is
dual to, but it does determine it enough so that vevs of all single trace 1/2
BPS operators in that state are uniquely determined to leading order in the
large N limit. These are precisely the vevs encoded in the asymptotics of the
LLM solutions. We extract these vevs for operators up to dimension 4 using
holographic renormalization and KK holography and show exact agreement with the
field theory expressions.Comment: 67 pages, 6 figures; v2: typos corrected, refs added; v3: expanded
explanations, more typos correcte
Entropy from AdS(3)/CFT(2)
We parametrize the (2+1)-dimensional AdS space and the BTZ black hole with
Fefferman-Graham coordinates starting from the AdS boundary. We consider
various boundary metrics: Rindler, static de Sitter and FRW. In each case, we
compute the holographic stress-energy tensor of the dual CFT and confirm that
it has the correct form, including the effects of the conformal anomaly. We
find that the Fefferman-Graham parametrization also spans a second copy of the
AdS space, including a second boundary. For the boundary metrics we consider,
the Fefferman-Graham coordinates do not cover the whole AdS space. We propose
that the length of the line delimiting the excluded region at a given time can
be identified with the entropy of the dual CFT on a background determined by
the boundary metric. For Rindler and de Sitter backgrounds our proposal
reproduces the expected entropy. For a FRW background it produces a
generalization of the Cardy formula that takes into account the vacuum energy
related to the expansion.Comment: major revision with several clarifications and corrections, 22 page
Real-time gauge/gravity duality: Prescription, Renormalization and Examples
We present a comprehensive analysis of the prescription we recently put
forward for the computation of real-time correlation functions using
gauge/gravity duality. The prescription is valid for any holographic
supergravity background and it naturally maps initial and final data in the
bulk to initial and final states or density matrices in the field theory. We
show in detail how the technique of holographic renormalization can be applied
in this setting and we provide numerous illustrative examples, including the
computation of time-ordered, Wightman and retarded 2-point functions in
Poincare and global coordinates, thermal correlators and higher-point
functions.Comment: 85 pages, 13 figures; v2: added comments and reference
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