568 research outputs found
Boundary Counterterms and the Thermodynamics of 2-D Black Holes
We utilize a novel method to study the thermodynamics of two dimensional type
0A black holes with constant RR flux. Our approach is based on the
Hamilton-Jacobi method of deriving boundary counterterms. We demonstrate this
approach by recovering the standard results for a well understood example,
Witten's black hole. Between this example and the 0A black hole we find
universal expressions for the entropy and black hole mass, as well as the
infra-red divergence of the partition function. As a non-trivial check of our
results we verify the first law of thermodynamics for these systems. Our
results for the mass disagree with the predictions of a proposed matrix model
dual of the 0A black hole.Comment: 27 pages, uses utarticle.cls; corrected typos and added reference
Extremal Black Holes in Dynamical Chern-Simons Gravity
Rapidly rotating black hole solutions in theories beyond general relativity
play a key role in experimental gravity, as they allow us to compute
observables in extreme spacetimes that deviate from the predictions of general
relativity. Such solutions are often difficult to find in
beyond-general-relativity theories due to the inclusion of additional fields
that couple to the metric non-linearly and non-minimally. In this paper, we
consider rotating black hole solutions in one such theory, dynamical
Chern-Simons gravity, where the Einstein-Hilbert action is modified by the
introduction of a dynamical scalar field that couples to the metric through the
Pontryagin density. We treat dynamical Chern-Simons gravity as an effective
field theory and work in the decoupling limit, where corrections are treated as
small perturbations from general relativity. We perturb about the
maximally-rotating Kerr solution, the so-called extremal limit, and develop
mathematical insight into the analysis techniques needed to construct solutions
for generic spin. First we find closed-form, analytic expressions for the
extremal scalar field, and then determine the trace of the metric perturbation,
giving both in terms of Legendre decompositions. Retaining only the first three
and four modes in the Legendre representation of the scalar field and the
trace, respectively, suffices to ensure a fidelity of over 99% relative to full
numerical solutions. The leading-order mode in the Legendre expansion of the
trace of the metric perturbation contains a logarithmic divergence at the
extremal Kerr horizon, which is likely to be unimportant as it occurs inside
the perturbed dynamical Chern-Simons horizon. The techniques employed here
should enable the construction of analytic, closed-form expressions for the
scalar field and metric perturbations on a background with arbitrary rotation.Comment: 25+9 pages (single column), 10 figures, 1 table; matches published
versio
Conformal gravity holography in four dimensions
We formulate four-dimensional conformal gravity with (Anti-)de Sitter
boundary conditions that are weaker than Starobinsky boundary conditions,
allowing for an asymptotically subleading Rindler term concurrent with a recent
model for gravity at large distances. We prove the consistency of the
variational principle and derive the holographic response functions. One of
them is the conformal gravity version of the Brown-York stress tensor, the
other is a `partially massless response'. The on-shell action and response
functions are finite and do not require holographic renormalization. Finally,
we discuss phenomenologically interesting examples, including the most general
spherically symmetric solutions and rotating black hole solutions with
partially massless hair.Comment: 5pp; v2: Minor clarifications and edits, added references. Phys. Rev.
Lett. versio
Black Hole Thermodynamics and Hamilton-Jacobi Counterterm
We review the construction of the universal Hamilton-Jacobi counterterm for
dilaton gravity in two dimensions, derive the corresponding result in the
Cartan formulation and elaborate further upon black hole thermodynamics and
semi-classical corrections. Applications include spherically symmetric black
holes in arbitrary dimensions with Minkowski- or AdS-asymptotics, the BTZ black
hole and black holes in two-dimensional string theory.Comment: 9 pages, proceedings contribution to QFEXT07 submitted to IJMPA, v2:
added Re
Menagerie of AdS boundary conditions
We consider different sets of AdS boundary conditions for the
Jackiw-Teitelboim model in the linear dilaton sector where the dilaton is
allowed to fluctuate to leading order at the boundary of the Poincar\'e disk.
The most general set of boundary condtions is easily motivated in the gauge
theoretic formulation as a Poisson sigma model and has an
current algebra as asymptotic symmetries. Consistency of the variational
principle requires a novel boundary counterterm in the holographically
renormalized action, namely a kinetic term for the dilaton. The on-shell action
can be naturally reformulated as a Schwarzian boundary action. While there can
be at most three canonical boundary charges on an equal-time slice, we consider
all Fourier modes of these charges with respect to the Euclidean boundary time
and study their associated algebras. Besides the (centerless)
current algebra we find for stricter boundary conditions a
Virasoro algebra, a warped conformal algebra and a current
algebra. In each of these cases we get one half of a corresponding symmetry
algebra in three-dimensional Einstein gravity with negative cosmological
constant and analogous boundary conditions. However, on-shell some of these
algebras reduce to finite-dimensional ones, reminiscent of the on-shell
breaking of conformal invariance in SYK. We conclude with a discussion of
thermodynamical aspects, in particular the entropy and some Cardyology.Comment: 42 pp, 5 figs, v2: added ref
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