3,830 research outputs found
General (Anti-)de Sitter Black Holes in Five Dimensions
We find a general class of rotating charged black hole solutions to N=2, D=5
gauged supergravity coupled to vector supermultiplets. The supersymmetry
properties of these solutions are studied, and their mass and angular momenta
are obtained. We also compute the stress tensor of the dual D=4, N=4 super
Yang-Mills theory in the limit of strong `t Hooft coupling. It is shown that
closed timelike curves occur outside the horizon, indicating loss of unitarity
in the dual CFT. For imaginary coupling constant of the gravitini to the gauge
fields, one can obtain multi-centered rotating charged de Sitter black holes.
Some physical properties of these solutions are also discussed.Comment: 22 pages, LaTeX, some explanations concerning the appearance of
closed timelike curves outside the horizon added in section 5.1, updated
references, published versio
Theory of Coherent -Axis Josephson Tunneling between Layered Superconductors
We calculate exactly the Josephson current for -axis coherent tunneling
between two layered superconductors, each with internal coherent tight-binding
intra- and interlayer quasiparticle dispersions. Our results also apply when
one or both of the superconductors is a bulk material, and include the usually
neglected effects of surface states. For weak tunneling, our results reduce to
our previous results derived using the tunneling Hamiltonian. Our results are
also correct for strong tunneling. However, the -axis tunneling results of
Tanaka and Kashiwaya are shown to be incorrect in any limit. In addition, we
consider the -axis coherent critical current between two identical layered
superconductors twisted an angle about the -axis with respect to
each other. Regardless of the order parameter symmetry, our coherent tunneling
results using a tight-binding intralayer quasiparticle dispersion are
inconsistent with the recent -axis twist bicrystal
BiSrCaCuO twist junction experiments of Li {\it et
al.}Comment: 11 pages, 13 figures, submitted to Physical Review
Causality Violation and Naked Time Machines in AdS_5
We study supersymmetric charged rotating black holes in AdS, and show
that closed timelike curves occur outside the event horizon. Also upon lifting
to rotating D3 brane solutions of type IIB supergravity in ten dimensions,
closed timelike curves are still present. We believe that these causal
anomalies correspond to loss of unitarity in the dual , D=4 super
Yang-Mills theory, i.e. the chronology protection conjecture in the AdS bulk is
related to unitarity bounds in the boundary CFT. We show that no charged or
uncharged geodesic can penetrate the horizon, so that the exterior region is
geodesically complete. These results still hold true in the quantum case,
i.~e.~the total absorption cross section for Klein-Gordon scalars propagating
in the black hole background is zero. This suggests that the effective
temperature is zero instead of assuming the naively found imaginary value.Comment: 22 pages, Latex, uses JHEP.cls, 1 figure. v3: comments on unitarity
in CFT and 2 references added. v4: changes in final remarks, final version to
appear in JHE
Strong coupling expansion and Seiberg-Witten-Whitham equations
We study the Seiberg-Witten-Whitham equations in the strong coupling regime
of the N=2 super Yang-Mills theory in the vicinity of the maximal
singularities. In the case of SU(2) the Seiberg-Witten-Whitham equations fix
completely the strong coupling expansion. For higher rank SU(N) they provide a
set of non-trivial constraints on the form of this expansion. As an example, we
study the off-diagonal couplings at the maximal point for which we propose an
ansatz that fulfills all the equations.Comment: 10 pages, LaTeX, no figures; v2: The expression for the off-diagonal
couplings has been corrected and numerical checks have been extended. One
reference adde
First Law, Counterterms and Kerr-AdS_5 Black Holes
We apply the counterterm subtraction technique to calculate the action and
other quantities for the Kerr--AdS black hole in five dimensions using two
boundary metrics; the Einstein universe and rotating Einstein universe with
arbitrary angular velocity. In both cases, the resulting thermodynamic
quantities satisfy the first law of thermodynamics. We point out that the
reason for the violation of the first law in previous calculations is that the
rotating Einstein universe, used as a boundary metric, was rotating with an
angular velocity that depends on the black hole rotation parameter. Using a new
coordinate system with a boundary metric that has an arbitrary angular
velocity, one can show that the resulting physical quantities satisfy the first
law.Comment: 19 pages, 1 figur
Skyrmion and Skyrme-Black holes in de Sitter spacetime
Numerical arguments are presented for the existence of regular and black hole
solutions of the Einstein-Skyrme equations with a positive cosmological
constant. These classical configurations approach asymptotically the de Sitter
spacetime. The main properties of the solutions and the differences with
respect to the asymptotically flat ones are discussed. It particular our
results suggest that, for a positive cosmological constant, the mass evaluated
as timelike infinity in infinite. Special emphasis is set to De Sitter black
holes Skyrmions which display two horizons.Comment: 11 pages, 4 figure
Time Correlation Functions of Three Classical Heisenberg Spins on an Isosceles Triangle and on a Chain: Strong Effects of Broken Symmetry
At arbitrary temperature , we solve for the dynamics of single molecule
magnets composed of three classical Heisenberg spins either on a chain with two
equal exchange constants , or on an isosceles triangle with a third,
different exchange constant . As T\rightrarrow\infty, the Fourier
transforms and long-time asymptotic behaviors of the two-spin time correlation
functions are evaluated exactly. The lack of translational symmetry on a chain
or an isosceles triangle yields time correlation functions that differ
strikingly from those on an equilateral trinagle with . At low ,
the Fourier transforms of the two autocorrelation functions with
show one and four modes, respectively. For a semi-infinite range, one
mode is a central peak. At the origin of this range, this mode has a novel
scaling form.Comment: 9 pages, 14 figures, accepted for publication in Phys. Rev.
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