5,938 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

### 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

### 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

### Resolved Conifolds in Supergravity Solutions

We construct generalized 11D supergravity solutions of fully localized
intersecting D2/D4 brane systems. These solutions are obtained by embedding
six-dimensional resolved Eguchi-Hanson conifolds lifted to M-theory. We reduce
these solutions to ten dimensions, obtaining new D-brane systems in type IIA
supergravity. We discuss the limits in which the dynamics of the D2 brane
decouples from the bulk for these solutions.Comment: 9 pages, 2 figures, minor changes, references added, version to
appear in Phys. Rev.

### Unitarity issue in BTZ black holes

We study the wave equation for a massive scalar in three-dimensional
AdS-black hole spacetimes to understand the unitarity issues in a semiclassical
way. Here we introduce four interesting spacetimes: the non-rotating BTZ black
hole (NBTZ), pure AdS spacetime (PADS), massless BTZ black hole (MBTZ), and
extremal BTZ black hole (EBTZ). Our method is based on the potential analysis
and solving the wave equation to find the condition for the frequency $\omega$
exactly. In the NBTZ case, one finds the quasinormal (complex and discrete)
modes which signals for a non-unitary evolution. Real and discrete modes are
found for the PADS case, which means that it is unitary obviously. On the other
hand, we find real and continuous modes for the two extremal black holes of
MBTZ and EBTZ. It suggests that these could be candidates for the unitary
system.Comment: 14 pages, contracted version to appear in MPL

### High energy QCD from Planckian scattering in AdS and the Froissart bound

We reanalyze high energy QCD scattering regimes from scattering in cut-off
AdS via gravity-gauge dualities (a la Polchinski-Strassler). We look at 't
Hooft scattering, Regge behaviour and black hole creation in AdS. Black hole
creation in the gravity dual is analyzed via gravitational shockwave
collisions. We prove the saturation of the QCD Froissart unitarity bound,
corresponding to the creation of black holes of AdS size, as suggested by
Giddings.Comment: 39 pages, latex, clarifying comments added throughout at referee's
request, version to be published in PR

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