4,077 research outputs found
A thermodynamical model for non-extremal black p-brane
We show that the correct entropy, temperature (and absorption probability) of
non-extremal black p-brane can be reproduced by a certain thermodynamical model
when maximizing its entropy. We show that the form of the model is related to
the geometrical similarity of non-extremal and near extremal black p-brane at
near horizon region, and argue about the appropriateness of the model.Comment: Almost the same version as the paper appeared in Physical Review
Brane Dualities in Non-relativistic Limit
We analyze brane dualities in the non-relativistic limit of the worldvolume
actions. In particular we have analyzed how the non-relativistic M2-brane is
related via these dualities to non-relativistic D2-brane, non-relativistic IIA
fundamental string and also, by using T-duality, to non-relativistic D1-string.
These actions coincide with ones obtained from relativistic actions by taking
non-relativistic limit, showing that the non-relativistic limit and the
dualities commute in these cases.Comment: 21 pages, 1 figur
Non-Relativistic Superstrings: A New Soluble Sector of AdS_5xS^5
We find a new sector of string theory in AdS_5xS^5 describing
non-relativistic superstrings in that geometry. The worldsheet theory of
non-relativistic strings in AdS_5xS^5 is derived and shown to reduce to a
supersymmetric free field theory in AdS_2. Non-relativistic string theory
provides a new calculable setting in which to study holography.Comment: 29 pages, LATEX forma
Antibranes don't go black
When D-branes are inserted in flux backgrounds of opposite charge, the
resulting solution has a certain singularity in the fluxes. Recently it has
been argued, using numerical solutions, that for anti-D3 branes in the
Klebanov-Strassler background these singularities cannot be cloaked by a
horizon, which strongly suggests they are not physical. In this note we provide
an analytic proof that the singularity of all codimension-three antibrane
solutions (such as anti-D6 branes in massive type IIA supergravity or anti-D3
branes smeared on the T^3 of R^3xT^3 with fluxes) cannot be hidden behind a
horizon, and that the charge of black branes with smooth event horizons must
have the same sign as the charge of the flux background. Our result indicates
that infinitesimally blackening the antibranes immediately triggers brane-flux
annihilation, and strengthens the intuition that antibranes placed in flux with
positive charge immediately annihilate against it.Comment: 9 pages, 1 figur
Universal dS vacua in STU-models
Stable de Sitter solutions in minimal F-term supergravity are known to lie
close to Minkowski critical points. We consider a class of STU-models arising
from type IIB compactifications with generalised fluxes. There, we apply an
analytical method for solving the equations of motion for the moduli fields
based on the idea of treating derivatives of the superpotential of different
orders up to third as independent objects. In particular, supersymmetric and
no-scale Minkowski solutions are singled out by physical reasons. Focusing on
the study of dS vacua close to supersymmetric Minkowski points, we are able to
elaborate a complete analytical treatment of the mass matrix based on the
sGoldstino bound. This leads to a class of interesting universal dS vacua. We
finally explore a similar possibility around no-scale Minkowski points and
discuss some examples.Comment: 31 pages, 4 figures and 7 table
Microscopic Entropy of Non-dilatonic Branes: a 2D approach
We investigate non-dilatonic p-branes in the near-extremal, near-horizon
regime. A two-dimensional gravity model, obtained from dimensional reduction,
gives an effective description of the brane. We show that the AdS_p+2/CFT_p+1
correspondence at finite temperature admits an effective description in terms
of a AdS_2/CFT_1 duality endowed with a scalar field, which breaks the
conformal symmetry and generates a non-vanishing central charge. The entropy of
the CFT_1 is computed using Cardy formula. Fixing in a natural way a free,
dimensionless, parameter introduced in the model by a renormalization
procedure, we find exact agreement between the CFT_1 entropy and the
Bekenstein-Hawking entropy of the brane.Comment: 10 pages, no figure
The Pseudoscalar Meson Mass to Two Loops in Three-Flavor Partially Quenched PT
This paper presents a first study of the pseudoscalar meson masses to two
loops, or NNLO, within the supersymmetric formulation of partially quenched
chiral perturbation theory (PQPT). The expression for the pseudoscalar
meson mass in the case of three valence and three sea quarks with equal masses,
but different from each other, is given to , along with a
numerical analysis.Comment: 4 pages, one reference added, small changes in discussio
Repetition of contaminating question types when children and youths with intellectual disabilities are interviewed
Background The present study examined the effects of repeating questions in interviews investigating the possible sexual abuse of children and youths who had a variety of intellectual disabilities. We predicted that the repetition of option-posing and suggestive questions would lead the suspected victims to change their responses, making it difficult to understand what actually happened. Inconsistency can be a key factor when assessing the reliability of witnesses. Materials Case files and transcripts of investigative interviews with 33 children and youths who had a variety of intellectual disabilities were obtained from prosecutors in Sweden. The interviews involved 25 females and 9 males whose chronological ages were between 5.4 and 23.7 years when interviewed (M = 13.2 years). Results Six per cent of the questions were repeated at least once. The repetition of focused questions raised doubts about the reports because the interviewees changed their answers 40% of the time. Conclusions Regardless of the witnesses' abilities, it is important to obtain reports that are as accurate and complete as possible in investigative interviews. Because this was a field study, we did not know which responses were accurate, but repetitions of potentially contaminating questions frequently led the interviewees to contradict their earlier answers. This means that the interviewers' behaviour diminished the usefulness of the witnesses' testimony
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