3,324 research outputs found
Merger Transitions in Brane--Black-Hole Systems: Criticality, Scaling, and Self-Similarity
We propose a toy model for study merger transitions in a curved spaceime with
an arbitrary number of dimensions. This model includes a bulk N-dimensional
static spherically symmetric black hole and a test D-dimensional brane
interacting with the black hole. The brane is asymptotically flat and allows
O(D-1) group of symmetry. Such a brane--black-hole (BBH) system has two
different phases. The first one is formed by solutions describing a brane
crossing the horizon of the bulk black hole. In this case the internal induced
geometry of the brane describes D-dimensional black hole. The other phase
consists of solutions for branes which do not intersect the horizon and the
induced geometry does not have a horizon. We study a critical solution at the
threshold of the brane-black-hole formation, and the solutions which are close
to it. In particular, we demonstrate, that there exists a striking similarity
of the merger transition, during which the phase of the BBH-system is changed,
both with the Choptuik critical collapse and with the merger transitions in the
higher dimensional caged black-hole--black-string system.Comment: 9 pages 2 figures; additional remarks and references are added at
Section IX "Discussion
Conformal anomaly of (2,0) tensor multiplet in six dimensions and AdS/CFT correspondence
We compute the conformal anomaly of free d=6 superconformal (2,0) tensor
multiplet on generic curved background. Up to a trivial covariant
total-derivative term, it is given by the sum of the type A part proportional
to the 6-d Euler density, and the type B part containing three independent Weyl
invariants. Multiplied by factor 4N^3, the type B part of the anomaly
reproduces exactly the corresponding part of the conformal anomaly of large N
multiple M5-brane (2,0) theory as predicted (hep-th/9806087) by the AdS/CFT
correspondence. The coefficients of the type A anomaly differ by the factor 4/7
x 4 N^3, so that the free tensor multiplet anomaly does not vanish on a
Ricci-flat background. The coefficient 4N^3 is the same as found
(hep-th/9703040) in the comparison of the tensor multiplet theory and the d=11
supergravity results for the absorption cross-sections of gravitons by M5
branes, and in the comparison (hep-th/9911135) of 2- and 3-point stress tensor
correlators of the free tensor multiplet with the AdS_7 supergravity
predictions. The reason for this coincidence is that the three Weyl-invariant
terms in the anomaly are related to the and terms in the near flat
space expansion of the corresponding non-local effective action, and thus to
the 2-point and 3-point stress tensor correlators in flat background. At the
same time, the type A anomaly is related to the term in the non-local
part of the effective action, i.e. to a certain structure in the 4-point
correlation function of stress tensors.Comment: 20 pages, latex. v2: minor corrections, references adde
Accretion of Ghost Condensate by Black Holes
The intent of this letter is to point out that the accretion of a ghost
condensate by black holes could be extremely efficient. We analyze steady-state
spherically symmetric flows of the ghost fluid in the gravitational field of a
Schwarzschild black hole and calculate the accretion rate. Unlike minimally
coupled scalar field or quintessence, the accretion rate is set not by the
cosmological energy density of the field, but by the energy scale of the ghost
condensate theory. If hydrodynamical flow is established, it could be as high
as tenth of a solar mass per second for 10MeV-scale ghost condensate accreting
onto a stellar-sized black hole, which puts serious constraints on the
parameters of the ghost condensate model.Comment: 5 pages, 3 figures, REVTeX 4.0; discussion expande
Time evolution of a thin black ring via Hawking radiation
Black objects lose their mass and angular momenta through evaporation by
Hawking radiation, and the investigation of their time evolution has a long
history. In this paper, we study this problem for a five-dimensional doubly
spinning black ring. The black ring is assumed to emit only massless scalar
particles. We consider a thin black ring with a small thickness parameter,
, which can be approximated by a boosted Kerr string locally. We
show that a thin black ring evaporates with fixing its thickness parameter
. Further, in the case of an Emparan-Reall black ring, we derive
analytic formulas for the time evolution, which has one parameter to be
evaluated numerically. We find that the lifetime of a thin black ring is
shorter by a factor of compared to a five-dimensional
Schwarzschild black hole with the same initial mass. We also study detailed
properties of the Hawking radiation from the thin black ring, including the
energy and angular spectra of emitted particles.Comment: 28 pages, 6 figure
Rescattering effects in laser-assisted electron-atom bremsstrahlung
Rescattering effects in nonresonant spontaneous laser-assisted electron-atom
bremsstrahlung (LABrS) are analyzed within the framework of time-dependent
effective-range (TDER) theory. It is shown that high energy LABrS spectra
exhibit rescattering plateau structures that are similar to those that are
well-known in strong field laser-induced processes as well as those that have
been predicted theoretically in laser-assisted collision processes. In the
limit of a low-frequency laser field, an analytic description of LABrS is
obtained from a rigorous quantum analysis of the exact TDER results for the
LABrS amplitude. This amplitude is represented as a sum of factorized terms
involving three factors, each having a clear physical meaning. The first two
factors are the exact field-free amplitudes for electron-atom bremsstrahlung
and for electron-atom scattering, and the third factor describes free electron
motion in the laser field along a closed trajectory between the first
(scattering) and second (rescattering) collision events. Finally, a
generalization of these TDER results to the case of LABrS in a Coulomb field is
discussed
Parallel-propagated frame along null geodesics in higher-dimensional black hole spacetimes
In [arXiv:0803.3259] the equations describing the parallel transport of
orthonormal frames along timelike (spacelike) geodesics in a spacetime
admitting a non-degenerate principal conformal Killing-Yano 2-form h were
solved. The construction employed is based on studying the Darboux subspaces of
the 2-form F obtained as a projection of h along the geodesic trajectory. In
this paper we demonstrate that, although slightly modified, a similar
construction is possible also in the case of null geodesics. In particular, we
explicitly construct the parallel-transported frames along null geodesics in
D=4,5,6 Kerr-NUT-(A)dS spacetimes. We further discuss the parallel transport
along principal null directions in these spacetimes. Such directions coincide
with the eigenvectors of the principal conformal Killing-Yano tensor. Finally,
we show how to obtain a parallel-transported frame along null geodesics in the
background of the 4D Plebanski-Demianski metric which admits only a conformal
generalization of the Killing-Yano tensor.Comment: 17 pages, no figure
Interaction of higher-dimensional rotating black holes with branes
We study interaction of rotating higher dimensional black holes with a brane
in space-times with large extra dimensions. We demonstrate that in a general
case a rotating black hole attached to a brane can loose bulk components of its
angular momenta. A stationary black hole can have only those components of the
angular momenta which are connected with Killing vectors generating
transformations preserving a position of the brane. In a final stationary state
the null Killing vector generating the black hole horizon is tangent to the
brane. We discuss first the interaction of a cosmic string and a domain wall
with the 4D Kerr black hole. We then prove the general result for slowly
rotating higher dimensional black holes interacting with branes. The
characteristic time when a rotating black hole with the gravitational radius
reaches this final stationary state is , where
is the higher dimensional gravitational coupling constant, is the
brane tension, and is the number of extra dimensions.Comment: Version published in Class. Quant. Gra
Gravitational field of charged gyratons
We study relativistic gyratons which carry an electric charge. The
Einstein-Maxwell equations in arbitrary dimensions are solved exactly in the
case of a charged gyraton propagating in an asymptotically flat metric.Comment: 11 pages, some new comments and new references added. To appear in
Classical and Quantum Gravit
Covalently Binding the Photosystem I to Carbon Nanotubes
We present a chemical route to covalently couple the photosystem I (PS I) to
carbon nanotubes (CNTs). Small linker molecules are used to connect the PS I to
the CNTs. Hybrid systems, consisting of CNTs and the PS I, promise new
photo-induced transport phenomena due to the outstanding optoelectronic
properties of the robust cyanobacteria membrane protein PS I
Orbifolded Konishi from the Mirror TBA
Starting with a discussion of the general applicability of the simplified
mirror TBA equations to simple deformations of the AdS_5 x S^5 superstring, we
proceed to study a specific type of orbifold to which the undeformed simplified
TBA equations directly apply. We then use this set of equations, as well as
Luscher's approach, to determine the NLO wrapping correction to the energy of
what we call the orbifolded Konishi state, and show that they perfectly agree.
In addition we discuss wrapping corrections to the ground state energy of the
orbifolded model under consideration.Comment: 26 pages, 5 figures, v2: corrected typos, added a short discussion on
the ground state of the model; as submitted to J. Phys.
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