213 research outputs found
A tensor instability in the Eddington inspired Born-Infeld Theory of Gravity
In this paper we consider an extension to Eddington's proposal for the
gravitational action. We study tensor perturbations of a homogeneous and
isotropic space-time in the Eddington regime, where modifications to Einstein
gravity are strong. We find that the tensor mode is linearly unstable deep in
the Eddington regime and discuss its cosmological implications.Comment: 5 pages, approved by Phys. Rev. D, additional references and minor
modification
Graviton n-point functions for UV-complete theories in Anti-de Sitter space
We calculate graviton n-point functions in an anti-de Sitter black brane
background for effective gravity theories whose linearized equations of motion
have at most two time derivatives. We compare the n-point functions in Einstein
gravity to those in theories whose leading correction is quadratic in the
Riemann tensor. The comparison is made for any number of gravitons and for all
physical graviton modes in a kinematic region for which the leading correction
can significantly modify the Einstein result. We find that the n-point
functions of Einstein gravity depend on at most a single angle, whereas those
of the corrected theories may depend on two angles. For the four-point
functions, Einstein gravity exhibits linear dependence on the Mandelstam
variable s versus a quadratic dependence on s for the corrected theory.Comment: 29 page
Stable monopole and dyon solutions in the Einstein-Yang-Mills theory in asymptotically anti-de Sitter Space
A continuum of new monopole and dyon solutions in the Einstein-Yang-Mills
theory in asymptotically anti-de Sitter space are found. They are regular
everywhere and specified with their mass, and non-Abelian electric and magnetic
charges. A class of monopole solutions which have no node in non-Abelian
magnetic fields are shown to be stable against spherically symmetric linear
perturbations.Comment: 9 pages with 5 figures. Revised version. To appear in Phys Rev Let
Rotation and the AdS/CFT correspondence
In asymptotically flat space a rotating black hole cannot be in thermodynamic
equilibrium because the thermal radiation would have to be co-rotating faster
than light far from the black hole. However in asymptotically anti-de Sitter
space such equilibrium is possible for certain ranges of the parameters. We
examine the relationship between conformal field theory in rotating Einstein
universes of dimensions two to four and Kerr anti-de Sitter black holes in
dimensions three to five. The five dimensional solution is new. We find similar
divergences in the partition function of the conformal field theory and the
action of the black hole at the critical angular velocity at which the Einstein
rotates at the speed of light. This should be an interesting limit in which to
study large Yang-Mills.Comment: 24 pages, RevTeX, 1 figure, references adde
Topology, Quantum Gravity and Particle Physics
It is argued that quantum gravity has an interpretation as a topological
field theory provided a certain constraint from the path intergral measure is
respected. The constraint forces us to couple gauge and matter fields to
gravity for space - time dimensions different from 3. We then discuss possible
models which may be relevant to our universe.Comment: 18 pages, LaTeX. Replaced version corrects typos and has additional
reference
Noncommutative Geometry Inspired Rotating Black Hole in Three Dimensions
We find a new rotating black hole in three-dimensional anti-de Sitter space
using an anisotropic perfect fluid inspired by the noncommutative black hole.
We deduce the thermodynamical quantities of this black hole and compare them
with those of a rotating BTZ solution.Comment: 7 page
Magnetically charged solutions via an analog of the electric-magnetic duality in (2+1)-dimensional gravity theories
We find an analog of the electric-magnetic duality, which is a
transformation between magnetic and electric sectors of the static and
rotationally symmetric solutions in a class of (2+1)-dimensional
Einstein-Maxwell-Dilaton gravity theories. The theories in our consideration
include, in particular, one parameter class of theories continuously connecting
the Banados-Teitelboim-Zanelli (BTZ) gravity and the low energy string
effective theory. When there is no charge, we have or
symmetry, depending on a parameter that specifies each theory. Via the
transformation, we obtain exact magnetically charged solutions from the known
electrically charged solutions. We explain the relationship between the
transformation and symmetry, and comment on the -duality of the
string theory.Comment: 10 pages, RevTe
Three-Dimensional Gravity with Conformal Scalar and Asymptotic Virasoro Algebra
Strominger has derived the Bekenstein-Hawking entropy of the BTZ black hole
using asymptotic Virasoro algebra. We apply Strominger's method to a black hole
solution found by Martinez and Zanelli (MZ). This is a solution of
three-dimensional gravity with a conformal scalar field. The solution is not
, but it is asymptotically ; therefore, it has the asymptotic
Virasoro algebra. We compute the central charge for the theory and compares
Cardy's formula with the Bekenstein-Hawking entropy. It turns out that the
functional form does agree, but the overall numerical coefficient does not.
This is because this approach gives the "maximum possible entropy" for the
numerical coefficient.Comment: 26 pages, LaTeX; v2: minor correction
On massive gravitons in 2+1 dimensions
The Fierz-Pauli (FP) free field theory for massive spin 2 particles can be
extended, in a spacetime of (1+2) dimensions (3D), to a generally covariant
parity-preserving interacting field theory, in at least two ways. One is "new
massive gravity" (NMG), with an action that involves curvature-squared terms.
Another is 3D "bigravity", which involves non-linear couplings of the FP tensor
field to 3D Einstein-Hilbert gravity. We review the proof of the linearized
equivalence of both "massive 3D gravity" theories to FP theory, and we comment
on their similarities and differences.Comment: 6 pages, to appear in the proceedings of the Spanish Relativity
Meeting ERE2009, Bilbao; minor changes, reference adde
Shortcuts to high symmetry solutions in gravitational theories
We apply the Weyl method, as sanctioned by Palais' symmetric criticality
theorems, to obtain those -highly symmetric -geometries amenable to explicit
solution, in generic gravitational models and dimension. The technique consists
of judiciously violating the rules of variational principles by inserting
highly symmetric, and seemingly gauge fixed, metrics into the action, then
varying it directly to arrive at a small number of transparent, indexless,
field equations. Illustrations include spherically and axially symmetric
solutions in a wide range of models beyond D=4 Einstein theory; already at D=4,
novel results emerge such as exclusion of Schwarzschild solutions in cubic
curvature models and restrictions on ``independent'' integration parameters in
quadratic ones. Another application of Weyl's method is an easy derivation of
Birkhoff's theorem in systems with only tensor modes. Other uses are also
suggested.Comment: 10 page
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