2,152 research outputs found
A universal result on central charges in the presence of double-trace deformations
We study large N conformal field theories perturbed by relevant double-trace
deformations. Using the auxiliary field trick, or Hubbard-Stratonovich
transformation, we show that in the infrared the theory flows to another CFT.
The generating functionals of planar correlators in the ultraviolet and
infrared CFT's are shown to be related by a Legendre transform. Our main result
is a universal expression for the difference of the scale anomalies between the
ultraviolet and infrared fixed points, which is of order 1 in the large N
expansion. Our computations are entirely field theoretic, and the results are
shown to agree with predictions from AdS/CFT. We also remark that a certain
two-point function can be computed for all energy scales on both sides of the
duality, with full agreement between the two and no scheme dependence.Comment: 15 pages, latex2e, no figures. v2: references adde
Emission of charged particles from four- and five-dimensional black holes
Recently Das and Mathur found that the leading order Hawking emission rate of
neutral scalars by near-extremal black holes is exactly reproduced by a
string theoretic model involving intersecting D-branes. We show that the
agreement continues to hold for charged scalar emission. We further show that
similar agreement can be obtained for a class of near-extremal black
holes using a model inspired by M-theory. In this model, BPS saturated
black holes with four charges are realized in M-theory as 5-branes triply
intersecting over a string. The low-energy excitations are signals traveling on
the intersection string.Comment: 15 pages, latex; typos corrected, a reference adde
Absorption by Threebranes and the AdS/CFT Correspondence
In the first part of this talk I discuss two somewhat different supergravity
approaches to calculating correlation functions in strongly coupled Yang-Mills
theory. The older approach relates two-point functions to cross-sections for
absorption of certain incident quanta by threebranes. In this approach the
normalization of operators corresponding to the incident particles is fixed
unambiguously by the D3-brane DBI action. By calculating absorption
cross-sections of all partial waves of the dilaton we find corresponding
two-point functions at strong `t Hooft coupling and show that they are
identical to the weak coupling results. The newer approach to correlation
functions relates them to boundary conditions in AdS space. Using this method
we show that for a certain range of negative mass-squared there are two
possible operator dimensions corresponding to a given scalar field in AdS, and
indicate how to calculate correlation functions for either of these choices. In
the second part of the talk I discuss an example of AdS/CFT duality which
arises in the context of type 0 string theory. The CFT on N coincident electric
and magnetic D3-branes is argued to be stable for sufficiently weak `t Hooft
coupling. It is suggested that its transition to instability at a critical
coupling is related to singularity of planar diagrams.Comment: 14 pages, LaTeX; Talk at Strings '99, Potsdam, German
Gauge/gravity correspondence in accelerating universe
We discuss time-dependent backgrounds of type IIB supergravity realizing
gravitation duals of gauge theories formulated in de Sitter space-time as a
tool of embedding de Sitter in a supergravity. We show that only the
gravitational duals to non-conformal gauge theories are sensitive to a specific
value of a Hubble parameter. We consider two nontrivial solutions of this type:
a gravity dual to six-dimensional (1,1) little string theory, and to a
four-dimensional cascading SU(N+M)xSU(N) supersymmetric gauge theory (related
to fractional D3-branes on a singular conifold according to Klebanov et al), in
accelerating universe. In both cases we argue that the IR singularity of the
geometry is regulated by the expansion of the gauge theory background
space-time.Comment: 13 pages, harvmac, v2: reference added, v3: D3,NS5 discussion
improved, PRD versio
Entropy and Temperature of Black 3-Branes
We consider slightly non-extremal black 3-branes of type IIB supergravity and
show that their Bekenstein-Hawking entropy agrees, up to a mysterious factor,
with an entropy derived by counting non-BPS excitations of the Dirichlet
3-brane. These excitations are described in terms of the statistical mechanics
of a 3+1 dimensional gas of massless open string states. This is essentially
the classic problem of blackbody radiation. The blackbody temperature is
related to the temperature of the Hawking radiation. We also construct a
solution of type IIB supergravity describing a 3-brane with a finite density of
longitudinal momentum. For extremal momentum-carrying 3-branes the horizon area
vanishes. This is in agreement with the fact that the BPS entropy of the
momentum-carrying Dirichlet 3-branes is not an extensive quantity.Comment: 10 pages, LaTeX, minor revisions. v3: version that appeared in PR
Scalar Absorption and the Breaking of the World Volume Conformal Invariance
We investigate a version of fixed scalars for non-dilatonic branes which
correspond to dilatations of the brane world-volume. We obtain a cross-section
whose world-volume interpretation falls out naturally from an investigation of
the breaking of conformal invariance by the irrelevant Born-Infeld corrections
to Yang-Mills theory. From the same irrelevant world-volume operator we obtain
the leading correction to the cross-sections of minimal scalars. This
correction can be obtained in supergravity via an improved matching of inner
and outer solutions to the minimal wave equation.Comment: 20 pages, 2 figures. Minor change
Absorption by Branes and Schwinger Terms in the World Volume Theory
We study how coincident Dirichlet 3-branes absorb incident gravitons
polarized along their world volume. We show that the absorption cross-section
is determined by the central term in the correlator of two stress-energy
tensors. The existence of a non-renormalization theorem for this central charge
in four-dimensional N=4 supersymmetric Yang-Mills theories shows that the
leading term at low energies in the absorption cross-section is not
renormalized. This guarantees that the agreement of the cross-section with
semiclassical supergravity, found in earlier work, survives all loop
corrections. The connection between absorption of gravitons polarized along the
brane and Schwinger terms in the stress-energy correlators of the world volume
theory holds in general. We explore this connection to deduce some properties
of the stress-energy tensor OPE's for 2-branes and 5-branes in 11 dimensions,
as well as for 5-branes in 10 dimensions.Comment: 13 pages, latex, minor changes, version to appear in Physics Letters
Thermodynamics of spinning D3-branes
Spinning black three-branes in type IIB supergravity are thermodynamically
stable up to a critical value of the angular momentum density. Inside the
region of thermodynamic stability, the free energy from supergravity is roughly
reproduced by a naive model based on free N=4 super-Yang-Mills theory on the
world-volume. The field theory model correctly predicts a limit on angular
momentum density, but near this limit it does not reproduce the critical
exponents one can compute from supergravity. Analogies with Bose condensation
and modified matrix models are discussed, and a mean field theory improvement
of the naive model is suggested which corrects the critical exponents.Comment: 20 pages, 1 figure, small improvement
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