13 research outputs found
Higher derivative effects for 4d AdS gravity
Motivated by holography we explore higher derivative corrections to four-dimensional Anti-de Sitter (AdS) gravity. We point out that in such a theory the variational problem is generically not well-posed given only a boundary condition for the metric. However, when one evaluates the higher derivative terms perturbatively on a leading order Einstein solution, the equations of motion are always second order and therefore the variational problem indeed requires only a boundary condition for the metric. The equations of motion required to compute the spectrum around the corrected background are still generically higher order, with the additional boundary conditions being associated with new operators in the dual conformal field theory. We discuss which higher derivative curvature invariants are expected to arise in the four-dimensional action from a top-down perspective and compute the corrections to planar AdS black holes and to the spectrum around AdS in various cases. Requiring that the dual theory is unitary strongly constrains the higher derivative terms in the action, as the operators associated with the extra boundary conditions generically have complex conformal dimensions and non-positive norms
Unstable Giants
We find giant graviton solutions in Frolov's three parameter generalization
of the Lunin-Maldacena background. The background we study has
and .
This class of backgrounds provide a non-superymmetric example of the gauge
theory/gravity correspondence that can be tested quantitatively, as recently
shown by Frolov, Roiban and Tseytlin. The giant graviton solutions we find have
a greater energy than the point gravitons, making them unstable states. Despite
this, we find striking quantitative agreement between the gauge theory and
gravity descriptions of open strings attached to the giant.Comment: 1+24 pages, 2 figures; v2: coupling to NSNS B field included, refs
added and typos corrected; v3 new results on stability of giants included,
presentation improved, refs added; v4 final version to appear in Phys. Rev.
2PI Effective Action and Evolution Equations of N = 4 super Yang-Mills
We employ nPI effective action techniques to study N = 4 super Yang-Mills,
and write down the 2PI effective action of the theory. We also supply the
evolution equations of two-point correlators within the theory.Comment: 16 pages, 6 figures. Figure 2 replaced, approximation scheme
clarified, references adde
Deformed PP-waves from the Lunin-Maldacena Background
In this article we study a pp-wave limit of the Lunin-Maldacena background.
We show that the relevant string theory background is a homogeneous pp-wave. We
obtain the string spectrum. The dual field theory is a deformation of N=4 super
Yang-Mills theory. We have shown that, for a class of operators, at O(g_{YM}^2)
and at leading order in N, all contributions to the anomalous dimension come
from F-terms. We are able to identify the operator in the deformed super
Yang-Mills which is dual to the lowest string mode. By studying the undeformed
theory we are able to provide some evidence, directly in the field theory, that
a small set of nearly protected operators decouple. We make some comments on
operators in the Yang-Mills theory that are dual to excited string modes.Comment: 22 pages, 1 figure; Final version to appear in JHE
Holography for Einstein-Maxwell-dilaton theories from generalized dimensional reduction
We show that a class of Einstein-Maxwell-Dilaton (EMD) theories are related
to higher dimensional AdS-Maxwell gravity via a dimensional reduction over
compact Einstein spaces combined with continuation in the dimension of the
compact space to non-integral values (`generalized dimensional reduction').
This relates (fairly complicated) black hole solutions of EMD theories to
simple black hole/brane solutions of AdS-Maxwell gravity and explains their
properties. The generalized dimensional reduction is used to infer the
holographic dictionary and the hydrodynamic behavior for this class of theories
from those of AdS. As a specific example, we analyze the case of a black brane
carrying a wave whose universal sector is described by gravity coupled to a
Maxwell field and two neutral scalars. At thermal equilibrium and finite
chemical potential the two operators dual to the bulk scalar fields acquire
expectation values characterizing the breaking of conformal and generalized
conformal invariance. We compute holographically the first order transport
coefficients (conductivity, shear and bulk viscosity) for this system.Comment: v2, Important additions: (1) discussion of the entropy current, (2)
postulated zeta/eta bound is generically violated. Some comments and
references added, typos corrected. 50 page