On effective action of string theory flux compactifications

We discuss four dimensional effective actions of string theory flux compactifications. These effective actions describe four dimensional gravity coupled to overall Kahler modulus of the compactification manifold. We demonstrate the agreement between ten dimensional equations of motion of supergravity with localized branes, and equations of motion derived from the effective action. The agreement is lost however if one evaluates the full effective action on the equations of motion for a subset of the supergravity modes, provided these modes depend on-shell on the Kahler modulus.Comment: 25 pages; v2: refs adde

Gauge/string correspondence in curved space

We discuss Gubser-Klebanov-Polyakov proposal for the gauge/string theory correspondence for gauge theories in curved space. Specifically, we consider Klebanov-Tseytlin cascading gauge theory compactified on S^3. We explain regime when this gauge theory is a small deformation of the superconformal N=1 gauge theory on the world volume of regular D3-branes at the tip of the conifold. We study closed string states on the leading Regge trajectory in this background, and attempt to identify the dual gauge theory twist two operators.Comment: 26 pages, v2: refs adde

Anomaly Cancelations in Orientifolds with Quantized B Flux

We consider anomaly cancelations in Type IIB orientifolds on T^4/Z_N with quantized NS-NS sector background B-flux. For a rank b B-flux on T^4 (b is always even) and when N is even, the cancelation requires a 2^{b/2} multiplicity of states in the 59-open string sector. We identify the twisted sector R-R scalars and tensor multiplets which are involved in the Green-Schwarz mechanism. We give more details of the construction of these models and argue that consistency with the 2^{b/2} multiplicity of 59-sector states requires a modification of the relation between the open string 1-loop channel modulus and the closed string tree channel modulus in the 59-cylinder amplitudes.Comment: Revtex 3.0, 34 pages, 2 figures, references adde

Viscosity Bound and Causality in Superfluid Plasma

It was argued by Brigante et.al that the lower bound on the ratio of the shear viscosity to the entropy density in strongly coupled plasma is translated into microcausality violation in the dual gravitational description. Since transport properties of the system characterize its infrared dynamics, while the causality of the theory is determined by its ultraviolet behavior, the viscosity bound/microcausality link should not be applicable to theories that undergo low temperature phase transitions. We present an explicit model of AdS/CFT correspondence that confirms this fact.Comment: 27 pages, 5 figures. References added, typos fixe

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

Transport coefficients, membrane couplings and universality at extremality

We present an efficient method for computing the zero frequency limit of transport coefficients in strongly coupled field theories described holographically by higher derivative gravity theories. Hydrodynamic parameters such as shear viscosity and conductivity can be obtained by computing residues of poles of the off-shell lagrangian density. We clarify in which sense these coefficients can be thought of as effective couplings at the horizon, and present analytic, Wald-like formulae for the shear viscosity and conductivity in a large class of general higher derivative lagrangians. We show how to apply our methods to systems at zero temperature but finite chemical potential. Our results imply that such theories satisfy $\eta/s=1/4\pi$ universally in the Einstein-Maxwell sector. Likewise, the zero frequency limit of the real part of the conductivity for such systems is shown to be universally zero, and we conjecture that higher derivative corrections in this sector do not modify this result to all orders in perturbation theory.Comment: 29 pages, v2: Small text changes for clarity, typos correcte

Comments on supergravity dual of pure N=1 Super Yang Mills theory with unbroken chiral symmetry

Maldacena and Nunez [hep-th/0008001] identified a gravity solution describing pure N=1 Yang-Mills (YM) in the IR. Their (smooth) supergravity solution exhibits confinement and the U(1)_R chiral symmetry breaking of the dual YM theory, while the singular solution corresponds to the gauge theory phase with unbroken U(1)_R chiral symmetry. In this paper we discuss supersymmetric type IIB compactifications on resolved conifolds with torsion. We rederive singular background of [hep-th/0008001] directly from the supersymmetry conditions. This solution is the relevant starting point to study non-BPS backgrounds dual to the high temperature phase of pure YM. We construct the simplest black hole solution in this background. We argue that it has a regular Schwarzschild horizon and provides a resolution of the IR singularity of the chirally symmetric extremal solution as suggested in [hep-th/0011146].Comment: 34 pages, LaTeX, v2: references added, v3: section 2 reduced, minor clarifications, to be published in PR

Higher Derivative Corrections to R-charged Black Holes: Boundary Counterterms and the Mass-Charge Relation

We carry out the holographic renormalization of Einstein-Maxwell theory with curvature-squared corrections. In particular, we demonstrate how to construct the generalized Gibbons-Hawking surface term needed to ensure a perturbatively well-defined variational principle. This treatment ensures the absence of ghost degrees of freedom at the linearized perturbative order in the higher-derivative corrections. We use the holographically renormalized action to study the thermodynamics of R-charged black holes with higher derivatives and to investigate their mass to charge ratio in the extremal limit. In five dimensions, there seems to be a connection between the sign of the higher derivative couplings required to satisfy the weak gravity conjecture and that violating the shear viscosity to entropy bound. This is in turn related to possible constraints on the central charges of the dual CFT, in particular to the sign of c-a.Comment: 30 pages. v2: references added, some equations simplifie