59 research outputs found
Rational foundation of GR in terms of statistical mechanic in the AdS/CFT framework
In this article, we work out the microscopic statistical foundation of the
supergravity description of the simplest 1/2 BPS sector in the AdS(5)/CFT(4).
Then, all the corresponding supergravity observables are related to
thermodynamical observables, and General Relativity is understood as a
mean-field theory. In particular, and as an example, the Superstar is studied
and its thermodynamical properties clarified.Comment: 13 pages, 6 eps figures, latex, some improvements introduced,
reference added, typos correcte
M-theory Supertubes with Three and Four Charges
Using the covariant M5-brane action, we construct configurations
corresponding to supertubes with three and four charges. We derive the BPS
equations and study the full structure of the solutions. In particular, we find
new solutions involving arbitrariness in field strengths.Comment: 24 pages, references added and typos correcte
Coarse-Graining the Lin-Maldacena Geometries
The Lin-Maldacena geometries are nonsingular gravity duals to degenerate
vacuum states of a family of field theories with SU(2|4) supersymmetry. In this
note, we show that at large N, where the number of vacuum states is large,
there is a natural `macroscopic' description of typical states, giving rise to
a set of coarse-grained geometries. For a given coarse-grained state, we can
associate an entropy related to the number of underlying microstates. We find a
simple formula for this entropy in terms of the data that specify the geometry.
We see that this entropy function is zero for the original microstate
geometries and maximized for a certain ``typical state'' geometry, which we
argue is the gravity dual to the zero-temperature limit of the thermal state of
the corresponding field theory. Finally, we note that the coarse-grained
geometries are singular if and only if the entropy function is non-zero.Comment: 29 pages, LaTeX, 3 figures; v2 references adde
From Gravitons to Giants
We discuss exact quantization of gravitational fluctuations in the half-BPS
sector around AdSS background, using the dual super Yang-Mills
theory. For this purpose we employ the recently developed techniques for exact
bosonization of a finite number of fermions in terms of bosonic
oscillators. An exact computation of the three-point correlation function of
gravitons for finite shows that they become strongly coupled at
sufficiently high energies, with an interaction that grows exponentially in
. We show that even at such high energies a description of the bulk physics
in terms of weakly interacting particles can be constructed. The single
particle states providing such a description are created by our bosonic
oscillators or equivalently these are the multi-graviton states corresponding
to the so-called Schur polynomials. Both represent single giant graviton states
in the bulk. Multi-particle states corresponding to multi-giant gravitons are,
however, different, since interactions among our bosons vanish identically,
while the Schur polynomials are weakly interacting at high enough energies.Comment: v2-references added, minor changes and typos corrected; 24 pages,
latex, 3 epsf figure
A Monte-Carlo study of the AdS/CFT correspondence: an exploration of quantum gravity effects
In this paper we study the AdS/CFT correspondence for N=4 SYM with gauge
group U(N), compactified on S^3 in four dimensions using Monte-Carlo
techniques. The simulation is based on a particular reduction of degrees of
freedom to commuting matrices of constant fields, and in particular, we can
write the wave functions of these degrees of freedom exactly. The square of the
wave function is equivalent to a probability density for a Boltzman gas of
interacting particles in six dimensions. From the simulation we can extract the
density particle distribution for each wave function, and this distribution can
be interpreted as a special geometric locus in the gravitational dual. Studying
the wave functions associated to half-BPS giant gravitons, we are able to show
that the matrix model can measure the Planck scale directly. We also show that
the output of our simulation seems to match various theoretical expectations in
the large N limit and that it captures 1/N effects as statistical fluctuations
of the Boltzman gas with the expected scaling. Our results suggest that this is
a very promising approach to explore quantum corrections and effects in
gravitational physics on AdS spaces.Comment: 40 pages, 7 figures, uses JHEP. v2: references adde
Semi-classical Probe Strings on Giant Gravitons Backgrounds
In the first part of this paper we study two symmetries of the LLM
metric, both of which exchange black and white regions. One of them which can
be interpreted as the particle-hole symmetry is the symmetry of the whole
supergravity solution while the second one is just the symmetry of the metric
and changes the sign of the fivefrom flux. In the second part of the paper we
use closed string probes and their semi-classical analysis to compare the two
1/2 BPS deformations of , the smooth LLM geometry which
contains localized giant gravitons and the superstar case which is a solution
with naked singularity corresponding to smeared giants. We discuss the
realization of the symmetry in the semi-classical closed string probes
point of view.Comment: 29 pages, 6 .eps figures; v2: References adde
Extended Fermion Representation of Multi-Charge 1/2-BPS Operators in AdS/CFT -- Towards Field Theory of D-Branes --
We extend the fermion representation of single-charge 1/2-BPS operators in
the four-dimensional N=4 super Yang-Mills theory to general (multi-charge)
1/2-BPS operators such that all six directions of scalar fields play roles on
an equal footing. This enables us to construct a field-theorectic
representation for a second-quantized system of spherical D3-branes in the
1/2-BPS sector. The Fock space of D3-branes is characterized by a novel
exclusion principle (called `Dexclusion' principle), and also by a nonlocality
which is consistent with the spacetime uncertainty relation. The Dexclusion
principle is realized by composites of two operators, obeying the usual
canonical anticommutation relation and the Cuntz algebra, respectively. The
nonlocality appears as a consequence of a superselction rule associated with a
symmetry which is related to the scale invariance of the super Yang-Mills
theory. The entropy of the so-called superstars, with multiple charges, which
have been proposed to be geometries corresponding to the condensation of giant
gravitons is discussed from our viewpoint and is argued to be consistent with
the Dexclusion principle. Our construction may be regarded as a first step
towards a possible new framework of general D-brane field theory.Comment: 43 pages, 4 figures; version 2, corrected typos and added reference
Entropy of near-extremal black holes in AdS_5
We construct the microstates of near-extremal black holes in AdS_5 x S^5 as
gases of defects distributed in heavy BPS operators in the dual SU(N)
Yang-Mills theory. These defects describe open strings on spherical D3-branes
in the S^5, and we show that they dominate the entropy by directly enumerating
them and comparing the results with a partition sum calculation. We display new
decoupling limits in which the field theory of the lightest open strings on the
D-branes becomes dual to a near-horizon region of the black hole geometry. In
the single-charge black hole we find evidence for an infrared duality between
SU(N) Yang-Mills theories that exchanges the rank of the gauge group with an
R-charge. In the two-charge case (where pairs of branes intersect on a line),
the decoupled geometry includes an AdS_3 factor with a two-dimensional CFT
dual. The degeneracy in this CFT accounts for the black hole entropy. In the
three-charge case (where triples of branes intersect at a point), the decoupled
geometry contains an AdS_2 factor. Below a certain critical mass, the
two-charge system displays solutions with naked timelike singularities even
though they do not violate a BPS bound. We suggest a string theoretic
resolution of these singularities.Comment: LaTeX; v2: references and a few additional comments adde
The Library of Babel: On the origin of gravitational thermodynamics
We show that heavy pure states of gravity can appear to be mixed states to
almost all probes. For AdS_5 Schwarzschild black holes, our arguments are made
using the field theory dual to string theory in such spacetimes. Our results
follow from applying information theoretic notions to field theory operators
capable of describing very heavy states in gravity. For half-BPS states of the
theory which are incipient black holes, our account is exact: typical
microstates are described in gravity by a spacetime ``foam'', the precise
details of which are almost invisible to almost all probes. We show that
universal low-energy effective description of a foam of given global charges is
via certain singular spacetime geometries. When one of the specified charges is
the number of D-branes, the effective singular geometry is the half-BPS
``superstar''. We propose this as the general mechanism by which the effective
thermodynamic character of gravity emerges.Comment: LaTeX, 6 eps figures, uses young.sty and wick.sty; Version 2: typos
corrected, minor rewordings and clarifications, references adde
Microstate Dependence of Scattering from the D1-D5 System
We investigate the question of distinguishing between different microstates
of the D1-D5 system (with charges Q_1 and Q_5), by scattering with an
incoherent beam, composed of a supergravity probe, with central energy E_0 and
width (\Delta E). The scattering is studied in the dual CFT description in the
orbifold limit for finite R, where R is the radius of the circle on which the
D1 branes are wrapped. When R(\Delta E) >> 1, the absorption cross-section is
found to be independent of the microstate and identical to the leading
semiclassical answer computed from the naive geometry. For smaller (\Delta E),
the answer depends on the particular microstate, which we examine for both
typical and atypical microstates. We derive an upper bound for the leading
correction to the cross-section when 1/R >> \Delta E >> (the average energy gap
1/{R [sqrt(Q_1Q_5)]}. For a typical state the bound is proportional to the area
of the stretched horizon, [\sqrt(Q_1 Q_5)], up to [log (Q_1Q_5)] terms.
Furthermore, when E_0 << (\Delta E), the proportionality constant is a pure
number independent of all energy scales. Numerical calculations using
Lorentzian profiles show that the actual value of the correction is in fact
proportional to [sqrt(Q_1Q_5)] without the logarithmic factor. We offer some
speculations about how this result can be consistent with a resolution of the
naive geometry by higher derivative corrections to supergravity.Comment: 42 pages, 5 figure
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