6,593 research outputs found

### 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

### 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

### 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

### 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

- …