477 research outputs found
Tomograms of Spinning Black Holes
The classical internal structure of spinning black holes is vastly different
from that of static black holes. We consider spinning BTZ black holes, and
probe their interior from the gauge theory. Utilizing the simplicity of the
geometry and reverse engineering from the geodesics, we propose a thermal
correlator construction which can be interpreted as arising from two entangled
CFTs. By analytic continuation of these correlators, we can probe the Cauchy
horizon. Correlators that capture the Cauchy horizon in our work have a
structure closely related to those that capture the singularity in a
non-rotating BTZ. As expected, the regions beyond the Cauchy horizon are not
probed in this picture, protecting cosmic censorship.Comment: 41 pages, 7 figure
Cascading Quivers from Decaying D-branes
We use an argument analogous to that of Kachru, Pearson and Verlinde to argue
that cascades in L^{a,b,c} quiver gauge theories always preserve the form of
the quiver, and that all gauge groups drop at each step by the number M of
fractional branes. In particular, we demonstrate that an NS5-brane that sweeps
out the S^3 of the base of L^{a,b,c} destroys M D3-branes.Comment: 11 pages, 1 figure; v2: references adde
On the smoothness of multi-M2 brane horizons
We calculate the degree of horizon smoothness of multi- -brane solution
with branes along a common axis. We find that the metric is generically only
thrice continuously differentiable at any of the horizons. The four-form field
strength is found to be only twice continuously differentiable. We work with
Gaussian null-like co-ordinates which are obtained by solving geodesic
equations for multi- brane geometry. We also find different, exact
co-ordinate transformations which take the metric from isotropic co-ordinates
to co-ordinates in which metric is thrice differentiable at the horizon. Both
methods give the same result that the multi- brane metric is only thrice
continuously differentiable at the horizon.Comment: 24 pages, reference added, modified equation for non-singularity of
metri
Meta-Stable Supersymmetry Breaking in a Cooling Universe
We look at the recently proposed idea that susy breaking can be accomplished
in a meta-stable vacuum. In the context of one of the simplest models (the
Seiberg-dual of super-QCD), we address the following question: if we look at
this theory as it cools from high temperature, is it at all possible that we
can end up in a susy-breaking meta-stable vacuum? To get an idea about the
answer, we look at the free energy of the system at high temperature. We
conclude that the phase-structure of the free-energy as the temperature drops,
is indeed such that there is a second order phase transition in the direction
of the non-susy vacuum at a finite . On the other hand, the potential
barrier in the direction of the susy vacuum is there all the way till .Comment: writing full author name
Adaptive response to low dose of EMS or MMS in human peripheral blood lymphocytes
Human peripheral blood lymphocytes stimulated in vitro for 6 hr were exposed to a low (conditioning) dose of ethyl methanesulfonate (EMS; 1.5 x 10(-4) M) or methyl methanesulfonate (MMS; 1.5 x 10(-5) M). After 6 hr, the cells were treated with a high (challenging) concentration of the same agent (1.5 x 10(-3) M EMS or 1.5 x 10(-4) M MMS). The cells that received both conditioning and challenging doses became less sensitive to the induction of sister chromatid exchanges (SCEs) than those which did not receive the pretreatment with EMS or MMS. They responded with lower frequencies of SCEs. This suggests that conditioning dose of EMS or MMS has offered the lymphocytes to have decreased SCEs. This led to the realization that pre-exposure of lymphocytes to low dose can cause the induction of repair activity. This is a clear indication of the existence of adaptive response induced by alkylating agents whether it is ethylating or methylating in human lymphocytes in vitro
Symplectic potentials and resolved Ricci-flat ACG metrics
We pursue the symplectic description of toric Kahler manifolds. There exists
a general local classification of metrics on toric Kahler manifolds equipped
with Hamiltonian two-forms due to Apostolov, Calderbank and Gauduchon(ACG). We
derive the symplectic potential for these metrics. Using a method due to Abreu,
we relate the symplectic potential to the canonical potential written by
Guillemin. This enables us to recover the moment polytope associated with
metrics and we thus obtain global information about the metric. We illustrate
these general considerations by focusing on six-dimensional Ricci flat metrics
and obtain Ricci flat metrics associated with real cones over L^{pqr} and
Y^{pq} manifolds. The metrics associated with cones over Y^{pq} manifolds turn
out to be partially resolved with two blowup parameters taking special
(non-zero)values. For a fixed Y^{pq} manifold, we find explicit metrics for
several inequivalent blow-ups parametrised by a natural number k in the range
0<k<p. We also show that all known examples of resolved metrics such as the
resolved conifold and the resolution of C^3/Z_3 also fit the ACG
classification.Comment: LaTeX, 34 pages, 4 figures (v2)presentation improved, typos corrected
and references added (v3)matches published versio
Can Quantum de Sitter Space Have Finite Entropy?
If one tries to view de Sitter as a true (as opposed to a meta-stable)
vacuum, there is a tension between the finiteness of its entropy and the
infinite-dimensionality of its Hilbert space. We invetsigate the viability of
one proposal to reconcile this tension using -deformation. After defining a
differential geometry on the quantum de Sitter space, we try to constrain the
value of the deformation parameter by imposing the condition that in the
undeformed limit, we want the real form of the (inherently complex) quantum
group to reduce to the usual SO(4,1) of de Sitter. We find that this forces
to be a real number. Since it is known that quantum groups have
finite-dimensional representations only for root of unity, this suggests
that standard -deformations cannot give rise to finite dimensional Hilbert
spaces, ruling out finite entropy for q-deformed de Sitter.Comment: 10 pages, v2: references added, v3: minor corrections, abstract and
title made more in-line with the result, v4: published versio
The Black Di-Ring: An Inverse Scattering Construction
We use the inverse scattering method (ISM) to derive concentric
non-supersymmetric black rings. The approach used here is fully
five-dimensional, and has the modest advantage that it generalizes readily to
the construction of more general axi-symmetric solutions.Comment: v3: 2 subsections added, typos fixed, more refs, journal version. v4:
a transcription error in the ADM mass fixe
Type IIB Holographic Superfluid Flows
We construct fully backreacted holographic superfluid flow solutions in a
five-dimensional theory that arises as a consistent truncation of low energy
type IIB string theory. We construct a black hole with scalar and vector hair
in this theory, and study the phase diagram. As expected, the superfluid phase
ceases to exist for high enough superfluid velocity, but we show that the phase
transition between normal and superfluid phases is always second order. We also
analyze the zero temperature limit of these solutions. Interestingly, we find
evidence that the emergent IR conformal symmetry of the zero-temperature domain
wall is broken at high enough velocity.Comment: v3: Published version. Figures 5 and 6 corrected. 24 pages, 7 figure
Performance analysis of DCT and successive division based digital image watermarking scheme
In this article, a combined Discrete Cosine Transformation (DCT) and Successive Division based image watermarking scheme is proposed. In many spatial domain approaches, the watermark information is embedded into Least Significant Bits (LSBs) of host image. These LSBs are more vulnerable to noise and other unwanted information contents in the channel, in few cases these are subjected for modifications also. Many frequency domain approaches withstands LSB interference problem but utilizes more execution time. The proposed technique is a frequency domain approach which can withstand LSB attack and utilizes very less execution time than other existing approaches. Performance analysis is done based on robustness, imperceptibility, data embedding capacity and time of execution. The experimental results are better compared to other existing techniques
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