750 research outputs found
Reconstruction of inhomogeneous metric perturbations and electromagnetic four-potential in Kerr spacetime
We present a procedure that allows the construction of the metric
perturbations and electromagnetic four-potential, for gravitational and
electromagnetic perturbations produced by sources in Kerr spacetime. This may
include, for example, the perturbations produced by a point particle or an
extended object moving in orbit around a Kerr black hole. The construction is
carried out in the frequency domain. Previously, Chrzanowski derived the vacuum
metric perturbations and electromagnetic four-potential by applying a
differential operator to a certain potential . Here we construct
for inhomogeneous perturbations, thereby allowing the application of
Chrzanowski's method. We address this problem in two stages: First, for vacuum
perturbations (i.e. pure gravitational or electromagnetic waves), we construct
the potential from the modes of the Weyl scalars or .
Second, for perturbations produced by sources, we express in terms of
the mode functions of the source, i.e. the energy-momentum tensor or the electromagnetic current vector .Comment: 20 pages; few typos corrected and minor modifications made; accepted
to Phys. Rev.
Entanglement Interpretation of Black Hole Entropy in String Theory
We show that the entropy resulting from the counting of microstates of non
extremal black holes using field theory duals of string theories can be
interpreted as arising from entanglement. The conditions for making such an
interpretation consistent are discussed. First, we interpret the entropy (and
thermodynamics) of spacetimes with non degenerate, bifurcating Killing horizons
as arising from entanglement. We use a path integral method to define the
Hartle-Hawking vacuum state in such spacetimes and discuss explicitly its
entangled nature and its relation to the geometry. If string theory on such
spacetimes has a field theory dual, then, in the low-energy, weak coupling
limit, the field theory state that is dual to the Hartle-Hawking state is a
thermofield double state. This allows the comparison of the entanglement
entropy with the entropy of the field theory dual, and thus, with the
Bekenstein-Hawking entropy of the black hole. As an example, we discuss in
detail the case of the five dimensional anti-de Sitter, black hole spacetime
Dimensional reduction from entanglement in Minkowski space
Using a quantum field theoretic setting, we present evidence for dimensional
reduction of any sub-volume of Minkowksi space. First, we show that correlation
functions of a class of operators restricted to a sub-volume of D-dimensional
Minkowski space scale as its surface area. A simple example of such area
scaling is provided by the energy fluctuations of a free massless quantum field
in its vacuum state. This is reminiscent of area scaling of entanglement
entropy but applies to quantum expectation values in a pure state, rather than
to statistical averages over a mixed state. We then show, in a specific case,
that fluctuations in the bulk have a lower-dimensional representation in terms
of a boundary theory at high temperature.Comment: 9 pages, changes to presentation, some content corrections, version
published in JHE
Lodged in the throat: Internal infinities and AdS/CFT
In the context of AdS3/CFT2, we address spacetimes with a certain sort of
internal infinity as typified by the extreme BTZ black hole. The internal
infinity is a null circle lying at the end of the black hole's infinite throat.
We argue that such spacetimes may be described by a product CFT of the form
CFT-L * CFT-R, where CFT-R is associated with the asymptotically AdS boundary
while CFT-L is associated with the null circle. Our particular calculations
analyze the CFT dual of the extreme BTZ black hole in a linear toy model of
AdS3/CFT2. Since the BTZ black hole is a quotient of AdS3, the dual CFT state
is a corresponding quotient of the CFT vacuum state. This state turns out to
live in the aforementioned product CFT. We discuss this result in the context
of general issues of AdS/CFT duality and entanglement entropy.Comment: 11 pages, 2 figures; v2 - some typos corrected, minor revision
Off-center collisions in AdS_5 with applications to multiplicity estimates in heavy-ion collisions
We study the trapped surface produced by an off-center collision of
light-like, point-sourced shock waves in anti-de Sitter space. We find an
analytic expression for the shape of the trapped surface in the limit where the
energy of the shock waves is large and the impact parameter is not too large.
We use the area of the trapped surface to estimate a lower bound on the entropy
produced in the collision. We compare our results to particle multiplicity
measurements in heavy-ion collisions as interpreted through the Glauber model.
In an attempt to roughly simulate the effects of asymptotic freedom and
confinement in quantum chromodynamics, we also consider the effects of slicing
off parts of anti-de Sitter space.Comment: 43 pages, 12 figures, 2 appendice
Entanglement and Nonunitary Evolution
We consider a collapsing relativistic spherical shell for a free quantum
field. Once the center of the wavefunction of the shell passes a certain radius
R, the degrees of freedom inside R are traced over. We show that an observer
outside this region will determine that the evolution of the system is
nonunitary. We argue that this phenomenon is generic to entangled systems, and
discuss a possible relation to black hole physics.Comment: 14 pages, 1 figure; Added a clarification regarding the relation with
black hole physic
Comparison between chiral and meson-theoretic nucleon-nucleon potentials through (p,p') reactions
We use proton-nucleus reaction data at intermediate energies to test the
emerging new generation of chiral nucleon-nucleon (NN) potentials. Predictions
from a high quality one-boson-exchange (OBE) force are used for comparison and
evaluation. Both the chiral and OBE models fit NN phase shifts accurately, and
the differences between the two forces for proton-induced reactions are small.
A comparison to a chiral model with a less accurate NN description sets the
scale for the ability of such models to work for nuclear reactions.Comment: 6 pages, revtex, 4 eps-figure
Short distance properties of cascading gauge theories
We study the short distance (large momentum) properties of correlation
functions of cascading gauge theories by performing a tree-level computation in
their dual gravitational background. We prove that these theories are
holographically renormalizable; the correlators have only analytic ultraviolet
divergences, which may be removed by appropriate local counterterms. We find
that n-point correlation functions of properly normalized operators have the
expected scaling in the semi-classical gravity (large N) limit: they scale as
N_{eff}^{2-n} with N_{eff} proportional to ln(k/Lambda) where k is a typical
momentum. Our analysis thus confirms the interpretation of the cascading gauge
theories as renormalizable four-dimensional quantum field theories with an
effective number of degrees of freedom which logarithmically increases with the
energy.Comment: 47 pages, no figure
On the Resolution of the Time-Like Singularities in Reissner-Nordstrom and Negative-Mass Schwarzschild
Certain time-like singularities are shown to be resolved already in classical
General Relativity once one passes from particle probes to scalar waves. The
time evolution can be defined uniquely and some general conditions for that are
formulated. The Reissner-Nordstrom singularity allows for communication through
the singularity and can be termed "beam splitter" since the transmission
probability of a suitably prepared high energy wave packet is 25%. The high
frequency dependence of the cross section is w^{-4/3}. However, smooth
geometries arbitrarily close to the singular one require a finite amount of
negative energy matter. The negative-mass Schwarzschild has a qualitatively
different resolution interpreted to be fully reflecting. These 4d results are
similar to the 2d black hole and are generalized to an arbitrary dimension d>4.Comment: 47 pages, 5 figures. v2: See end of introduction for an important
note adde
Fourth sound of holographic superfluids
We compute fourth sound for superfluids dual to a charged scalar and a gauge
field in an AdS_4 background. For holographic superfluids with condensates that
have a large scaling dimension (greater than approximately two), we find that
fourth sound approaches first sound at low temperatures. For condensates that a
have a small scaling dimension it exhibits non-conformal behavior at low
temperatures which may be tied to the non-conformal behavior of the order
parameter of the superfluid. We show that by introducing an appropriate scalar
potential, conformal invariance can be enforced at low temperatures.Comment: 20 pages, 6 figures; removed a discussion on a variant of fourth
soun
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