557 research outputs found
Solution to the 3-loop -derivable Approximation for Scalar Thermodynamics
We solve the 3-loop -derivable approximation to the thermodynamics of
the massless field theory by reducing it to a 1-parameter variational
problem. The thermodynamic potential is expanded in powers of and ,
where is the coupling constant, is a variational mass parameter, and
is the temperature. There are ultraviolet divergences beginning at 6th
order in that cannot be removed by renormalization. However the finite
thermodynamic potential obtained by truncating after terms of 5th order in
and defines a stable approximation to the thermodynamic functions.Comment: 4 pages, 1 figur
Correlation functions in a cascading N=1 gauge theory from supergravity
We study fluctuations around the warped conifold supergravity solution of
Klebanov and Tseytlin [hep-th/0002159], known to be dual to a cascading N=1
gauge theory. Although this supergravity background is not asymptotically AdS,
corresponding to a non-conformal field theory, it is possible to apply the
usual methods of AdS/CFT duality to extract the high energy behavior of field
theory correlators by solving linearized equations of motion for fluctuations
around the background. We consider the Goldstone vector dual to the anomalous
R-symmetry current and compute its mass, which exactly matches the general
prediction of [hep-th/0009156]. We find the high energy 2-point functions for
the R-current and two other vectors. As expected, the R-current 2-point
function has a longitudinal part because R-symmetry is broken. We also
calculate the high energy 2-point function of the energy-momentum tensor from
fluctuations of modes in the graviton sector. This 2-point function has a trace
part corresponding to broken conformal symmetry.Comment: JHEP, 29 page
Some interesting violations of the Breitenlohner-Freedman bound
We demonstrate that AdS_5 x T^{pq} is unstable, in the sense of Breitenlohner
and Freedman, for unequal p and q. This settles, negatively, the long-standing
question of whether the T^{pq} manifolds for unequal p and q might correspond
to non-supersymmetric fixed points of the renormalization group. We also show
that the AdS_3 x S^7 vacuum of Sugimoto's USp(32) open string theory is
unstable. This explains, at a heuristic level, the apparent absence of a
heterotic string dual.Comment: 16 pages, latex. v2: minor correction
The holographic RG flow in a field theory on a curved background
As shown by Freedman, Gubser, Pilch and Warner, the RG flow in
super-Yang-Mills theory broken to an theory by the addition of a
mass term can be described in terms of a supersymmetric domain wall solution in
five-dimensional gauged supergravity. The FGPW flow is an example
of a holographic RG flow in a field theory on a flat background. Here we put
the field theory studied by Freedman, Gubser, Pilch and Warner on a curved
background, and we construct the supersymmetric domain wall solution
which describes the RG flow in this field theory. This solution is a curved
(non Ricci flat) domain wall solution. This example demonstrates that
holographic RG flows in supersymmetric field theories on a curved
background can be described in terms of curved supersymmetric domain wall
solutions.Comment: 14 pages, LaTe
Star product and the general Leigh-Strassler deformation
We extend the definition of the star product introduced by Lunin and
Maldacena to study marginal deformations of N=4 SYM. The essential difference
from the latter is that instead of considering U(1)xU(1) non-R-symmetry, with
charges in a corresponding diagonal matrix, we consider two Z_3-symmetries
followed by an SU(3) transformation, with resulting off-diagonal elements. From
this procedure we obtain a more general Leigh-Strassler deformation, including
cubic terms with the same index, for specific values of the coupling constants.
We argue that the conformal property of N=4 SYM is preserved, in both beta-
(one-parameter) and gamma_{i}-deformed (three-parameters) theories, since the
deformation for each amplitude can be extracted in a prefactor. We also
conclude that the obtained amplitudes should follow the iterative structure of
MHV amplitudes found by Bern, Dixon and Smirnov.Comment: 21 pages, no figures, JHEP3, v2: references added, v3: appendix A
added, v4: clarification in section 3.
Non-supersymmetric deformations of the dual of a confining gauge theory
We introduce a computational technique for studying non-supersymmetric
deformations of domain wall solutions of interest in AdS/CFT. We focus on the
Klebanov-Strassler solution, which is dual to a confining gauge theory. From an
analysis of asymptotics we find that there are three deformations that leave
the ten-dimensional supergravity solution regular and preserve the global
bosonic symmetries of the supersymmetric solution. Also, we show that there are
no regular near-extremal deformations preserving the global symmetries, as one
might expect from the existence of a gap in the gauge theory.Comment: 18 pages, latex, published as JHEP 0305 (2003) 03
Towards a Big Crunch Dual
We show there exist smooth asymptotically anti-de Sitter initial data which
evolve to a big crunch singularity in a low energy supergravity limit of string
theory. This opens up the possibility of using the dual conformal field theory
to obtain a fully quantum description of the cosmological singularity. A
preliminary study of this dual theory suggests that the big crunch is an
endpoint of evolution even in the full string theory. We also show that any
theory with scalar solitons must have negative energy solutions. The results
presented here clarify our earlier work on cosmic censorship violation in N=8
supergravity.Comment: 27 pages, 3 figures;v2:minor correction
D-Brane Potentials from Multi-Trace Deformations in AdS/CFT
It is known that certain AdS boundary conditions allow smooth initial data to
evolve into a big crunch. To study this type of cosmological singularity, one
can use the dual quantum field theory, where the non-standard boundary
conditions are reflected by the presence of a multi-trace potential unbounded
below. For specific AdS_4 and AdS_5 models, we provide a D-brane (or M-brane)
interpretation of the unbounded potential. Using probe brane computations, we
show that the AdS boundary conditions of interest cause spherical branes to be
pushed to the boundary of AdS in finite time, and that the corresponding
potential agrees with the multi-trace deformation of the dual field theory.
Systems with expanding spherical D3-branes are related to big crunch
supergravity solutions by a phenomenon similar to geometric transition.Comment: 26 pages, 3 figures, v4: a few typos fixed
AdS/QCD Phenomenological Models from a Back-Reacted Geometry
We construct a fully back-reacted holographic dual of a four-dimensional
field theory which exhibits chiral symmetry breaking. Two possible models are
considered by studying the effects of a five-dimensional field, dual to the
operator. One model has smooth geometry at all radii and the other
dynamically generates a cutoff at finite radius. Both of these models satisfy
Einstein's field equations. The second model has only three free parameters, as
in QCD, and we show that this gives phenomenologically consistent results. We
also discuss the possibility that in order to obtain linear confinement from a
back-reacted model it may be necessary to consider the condensate of a
dimension two operator.Comment: 13 pages, 4 figures, Replaced with minor correction
Proof of the MHV vertex expansion for all tree amplitudes in N=4 SYM theory
We prove the MHV vertex expansion for all tree amplitudes of N=4 SYM theory.
The proof uses a shift acting on all external momenta, and we show that every
N^kMHV tree amplitude falls off as 1/z^k, or faster, for large z under this
shift. The MHV vertex expansion allows us to derive compact and efficient
generating functions for all N^kMHV tree amplitudes of the theory. We also
derive an improved form of the anti-NMHV generating function. The proof leads
to a curious set of sum rules for the diagrams of the MHV vertex expansion.Comment: 40 pages, 7 figure
- …