1,356 research outputs found
Conformal description of horizon's states
The existence of black hole horizon is considered as a boundary condition to
be imposed on the fluctuating metrics. The coordinate invariant form of the
condition for class of spherically symmetric metrics is formulated. The
diffeomorphisms preserving this condition act in (arbitrary small) vicinity of
the horizon and form the group of conformal transformations of two-dimensional
space ( sector of the total space-time). The corresponding algebra
recovered at the horizon is one copy of the Virasoro algebra. For general
relativity in dimensions we find an effective two-dimensional theory
governing the conformal dynamics at the horizon universally for any .
The corresponding Virasoro algebra has central charge proportional to the
Bekenstein-Hawking entropy. Identifying the zero-mode configuration we
calculate . The counting of states of this horizon's conformal field
theory by means of Cardy's formula is in complete agreement with the
Bekenstein-Hawking expression for the entropy of black hole in dimensions.Comment: 13 pages, latex, no figures; the final version to appear in Phys.
Lett.
Space Noncommutativity Corrections to the Cardy-Verlinde Formula
In this letter we compute the corrections to the Cardy-Verlinde formula of
Schwarzschild black holes. These corrections stem from the space
noncommutativity. Because the Schwarzschild black holes are non rotating, to
the first order of perturbative calculations, there is no any effect on the
properties of black hole due to the noncommutativity of space.Comment: 7 pages, no figures, accepted for publication in Int. J. Mod. Phys.
Horizon State, Hawking Radiation and Boundary Liouville Model
We demonstrate that the near-horizon physics, the Hawking radiation and the
reflection off the radial potential barrier, can be understood entirely within
a conformal field theory picture in terms of one- and two-point functions in
the boundary Liouville theory. An important element in this demonstration is
the notion of {\it horizon state}, the Hawking radiation being interpreted as a
result of the transition of horizon state to the ordinary states propagating
outside black hole horizon.Comment: Revtex, 5pages; final version to appear in Phys.Rev.Let
Triple-horizon spherically symmetric spacetime and holographic principle
We present a family of spherically symmetric spacetimes, specified by the
density profile of a vacuum dark energy, which have the same global structure
as the de Sitter spacetime but the reduced symmetry which leads to a
time-evolving and spatially inhomogeneous cosmological term. It connects
smoothly two de Sitter vacua with different values of cosmological constant and
corresponds to anisotropic vacuum dark fluid defined by symmetry of its
stress-energy tensor which is invariant under the radial boosts. This family
contains a special class distinguished by dynamics of evaporation of a
cosmological horizon which evolves to the triple horizon with the finite
entropy, zero temperature, zero curvature, infinite positive specific heat, and
infinite scrambling time. Non-zero value of the cosmological constant in the
triple-horizon spacetime is tightly fixed by quantum dynamics of evaporation of
the cosmological horizon.Comment: Honorable Mentioned Essay - Gravity Research Foundation 2012;
submitted to Int. J. Mod. Phys.
Black Hole Attractors and the Topological String
A simple relationship of the form Z_BH = |Z_top|^2 is conjectured, where Z_BH
is a supersymmetric partition function for a four-dimensional BPS black hole in
a Calabi-Yau compactification of Type II superstring theory and Z_top is a
second-quantized topological string partition function evaluated at the
attractor point in moduli space associated to the black hole charges. Evidence
for the conjecture in a perturbation expansion about large graviphoton charge
is given. The microcanonical ensemble of BPS black holes can be viewed as the
Wigner function associated to the wavefunction defined by the topological
string partition function.Comment: 32 pages, harvma
Central Charge for AdS_2 Quantum Gravity
Two-dimensional Maxwell-dilaton quantum gravity on AdS_2 with radius
and a constant electric field E is studied. In conformal gauge, this is
equivalent to a CFT on a strip. In order to maintain consistent boundary
conditions, the usual conformal diffeomorphisms must be accompanied by a
certain U(1) gauge transformation. The resulting conformal transformations are
generated by a twisted stress tensor, which has a central charge where k is the level of the U(1) current. This is an AdS_2 analog of
the Brown-Henneaux formula for the central charge of quantum
gravity on AdS_3
Microscopic Entropy of N=2 Extremal Black Holes
String theory is used to compute the microscopic entropy for several examples
of black holes in compactifications with supersymmetry. Agreement with
the Bekenstein-Hawking entropy and the moduli-independent area formula is
found in all cases.Comment: 9 pages, no figures, uses harvma
What We Don't Know about BTZ Black Hole Entropy
With the recent discovery that many aspects of black hole thermodynamics can
be effectively reduced to problems in three spacetime dimensions, it has become
increasingly important to understand the ``statistical mechanics'' of the
(2+1)-dimensional black hole of Banados, Teitelboim, and Zanelli (BTZ). Several
conformal field theoretic derivations of the BTZ entropy exist, but none is
completely satisfactory, and many questions remain open: there is no consensus
as to what fields provide the relevant degrees of freedom or where these
excitations live. In this paper, I review some of the unresolved problems and
suggest avenues for their solution.Comment: 24 pages, LaTeX, no figures; references added, brief discussion of
relation to string theory added; to appear in Class. Quant. Gra
Wilson loops in large N field theories
We propose a method to calculate the expectation values of an operator
similar to the Wilson loop in the large N limit of field theories. We consider
N=4 3+1 dimensional super-Yang-Mills. The prescription involves calculating the
area of a fundamental string worldsheet in certain supergravity backgrounds. We
also consider the case of coincident M-theory fivebranes where one is lead to
calculating the area of M-theory two-branes. We briefly discuss the computation
for 2+1 dimensional super-Yang-Mills with sixteen supercharges which is
non-conformal. In all these cases we calculate the energy of quark-antiquark
pair.Comment: 12 pages, harvmac. v2: sign in eqn. (5.6) corrected, v3 typo
correcte
D-brane recoil
It is shown that there are logarithmic operators in D-brane backgrounds that
lead to infrared divergences in open string loop amplitudes. These divergences
can be cancelled by changing the closed string background by operators that
correspond to the D-brane moving with constant velocity after some instant in
time, since it is precisely such operators that give rise to the appropriate
ultraviolet divergences in the closed string channel.Comment: Plain TeX, 5 page
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