Tunneling between de Sitter and anti de Sitter black holes in a noncommutative D3-brane formalism

We obtain dS and AdS generalized Reissner-Nordstrom like black hole geometries in a curved D3-brane frame-work, underlying a noncommutative gauge theory on the brane-world. The noncommutative scaling limit is explored to investigate a possible tunneling of an AdS vacuum in string theory to dS vacuum in its low energy gravity theory. The Hagedorn transition is invoked into its self-dual gauge theory to decouple the gauge nonlinearity from the dS geometry, which in turn is shown to describe a pure dS vacuum.Comment: 7-page

Vertex Operators of Super Wilson Loops

We study the supersymmetric Wilson loop as introduced by Caron-Huot, which attaches to lightlike polygons certain edge and vertex operators, whose shape is determined by supersymmetry constraints. We state explicit formulas for the vertex operators to all orders in the Gra{\ss}mann expansion, thus filling a gap in the literature. This is achieved by deriving a recursion formula out of the supersymmetry constraints.Comment: 11 page

Universal Low-Energy Dynamics for Rotating Black Holes

Fundamental string theory has been used to show that low energy excitations of certain black holes are described by a two dimensional conformal field theory. This picture has been found to be extremely robust. In this paper it is argued that many essential features of the low energy effective theory can be inferred directly from a semiclassical analysis of the general Kerr-Newman solution of supersymmetric four-dimensional Einstein-Maxwell gravity, without using string theory. We consider the absorption and emission of scalars with orbital angular momentum, which provide a sensitive probe of the black hole. We find that the semiclassical emission rates -including superradiant emission and greybody factors - for such scalars agree in striking detail with those computed in the effective conformal field theory, in both four and five dimensions. Also the value of the quantum mass gap to the lowest-lying excitation of a charge-$Q$ black hole, $E_{gap}=1/8Q^3$ in Planck units, can be derived without knowledge of fundamental string theory.Comment: 24 pages, no figures. Typos corrected, some comments adde

Fermion Mass Hierarchy from the Soft Wall

We develop a 5d model for ElectroWeak physics based on a non compact warped extra dimension of finite length, known as the soft wall scenario, where all the dynamical degrees of freedom propagate in the 5d bulk. We solve the equations of motion and find the allowed spectra, showing that the mass of the lightest fermionic mode behaves as a power law of the effective 4d Yukawa coupling constant, with the exponent being the corresponding fermionic 5d bulk mass. Precisely this non universal behavior allows us to reproduce the hierarchy between the Standard Model (SM) fermion masses (from neutrinos to the top quark) with non-hierarchical fermionic bulk masses.Comment: 26 pages, 4 figures, minor changes, one figured added, version to be publish in PR

1+1-dimensional p-wave superconductors from intersecting D-branes

In this work we explore 1+1 dimensional p-wave superconductors using the probe D-brane construction. Specifically, we choose three intersecting D-brane models: D1/D5, D2/D4 and D3/D3 systems. According to the dilaton running behavior, we denote the former two systems as nonconformal models and the last system as conformal. We find that all three models are qualitatively similar in describing superconducting condensate as well as some basic features (such as the gap formation and DC superconductivity) of superconducting conductivity. There also exist some differences among the three models as far as the AC conductivity is concerned. Specifically, for D3/D3 model there is no peak at nonzero frequency for the imaginary part of the conductivity, which is present in the nonconformal models; their asymptotic behaviors are different-for D1/D5 the real part of the AC conductivity approaches one at large frequency limit, for D2/D4 it slowly goes to a certain nonzero constant smaller than one and for D3/D3 it goes to zero. We find the profile of the AC conductivity for the D1/D5 system is very similar to that of higher dimensional p-wave superconductors.Comment: v2: matched with the published versio

The static potential in {\cal N}=4 supersymmetric Yang-Mills at weak coupling

We compute the static potential associated to the locally 1/2 BPS Wilson loop in ${\cal N}$=4 supersymmetric Yang-Mills theory with ${\cal O}(\lambda^2/r)$ accuracy. We also resum the leading logarithms, of ${\cal O}(\lambda^{n+1}\ln^n\lambda/r)$, and show the structure of the renormalization group equation at next-to-leading order in the multipole expansion. In order to obtain these results it is crucial the use of an effective theory for the ultrasoft degrees of freedom. We develop this theory up to next-to-leading order in the multipole expansion. Using the same formalism we also compute the leading logarithms, of ${\cal O}(\lambda^{n+3}\ln^n\lambda/r)$, of the static potential associated to an ordinary Wilson loop in the same theory.Comment: 6 pages, 1 figure. Two references added, misprints corrected. Computation of the static potential associated to the ordinary static Wilson loop incorporate

On the quantization of the N=2 supersymmetric non linear sigma model

A method for quantizing the bidimensional N=2 supersymmetric non-linear sigma model is developed. This method is both covariant under coordinate transformations (concerning the order relevant for calculations) and explicitly N=2 supersymmetric. The OPE of the supercurrent is computed accordingly, including also the dilaton. By imposing the N=2 superconformal algebra the equations for the metric and dilaton are obtained. In particular, they imply that the dilaton is a constant.Comment: 16 page

Violation of the holographic bulk viscosity bound

Motivated by gauge theory/string theory correspondence, a lower bound on the bulk viscosity of strongly coupled gauge theory plasma was proposed in arXiv:0708.3459. We consider strongly coupled N=4 supersymmetric Yang-Mills plasma compactified on a two-manifold of constant curvature beta. We show that the effective (1+1)-dimensional hydrodynamic description of the system is governed by the bulk viscosity violating the bound of arXiv:0708.3459, once beta<0.Comment: 17 pages, 3 figure

D-brane Description of New Open String Solutions in AdS(5)

In this paper we find D-brane descriptions of some of new open string solutions that were found in 0804.3438[hep-th]. These D5-brane and D3-brane configurations give gravitational dual descriptions of Wilson loops in some particular representations.Comment: 13 pages, references adde

The Conformal Limit of the 0A Matrix Model and String Theory on AdS(2)

We analyze the conformal limit of the matrix model describing flux backgrounds of two dimensional type 0A string theory. This limit is believed to be dual to an AdS(2) background of type 0A string theory. We show that the spectrum of this limit is identical to that of a free fermion on AdS(2), suggesting that there are no closed string excitations in this background.Comment: 17 pages, 1 figur