481 research outputs found
Kerr/CFT Correspondence in the Low Energy Limit of Heterotic String Theory
We investigate the recently proposed Kerr/CFT correspondence in the context
of heterotic string theory. The Kerr/CFT correspondence states that the
near-horizon states of an extremal four (or higher) dimensional black hole
could be identified with a certain chiral conformal field theory under the
conjecture that the central charges from the non-gravitational fields vanish.
The corresponding Virasoro algebra is generated by a class of diffeomorphisms
which preserves the appropriate boundary conditions on the near-horizon
geometry. To understand the chiral conformal field theory, we consider the
class of extremal Kerr-Sen black hole (that contains three non-gravitational
fields) as a class of solutions in the low energy limit (effective field
theory) of heterotic string theory. We derive the expression of the conserved
charges for the extremal Kerr-Sen solutions that contain dilaton, abelian gauge
filed and antisymmetric tensor filed. We confirm and extend the validity of the
conjecture (that the central charges from the non-gravitational fields vanish)
for theories including antisymmetric tensor fields. We combine the calculated
central charges with the expected form of the temperature using the Cardy
formula to obtain the entropy of the extremal black hole microscopically; in
agreement with the macroscopic Bekenstein-Hawking entropy of the extremal black
hole.Comment: 14 pages, a few sentences added to the introduction, version to
appear in JHE
Topologically Massive Gravity and Ricci-Cotton Flow
We consider Topologically Massive Gravity (TMG), which is three dimensional
general relativity with a cosmological constant and a gravitational
Chern-Simons term. When the cosmological constant is negative the theory has
two potential vacuum solutions: Anti-de Sitter space and Warped Anti-de Sitter
space. The theory also contains a massive graviton state which renders these
solutions unstable for certain values of the parameters and boundary
conditions. We study the decay of these solutions due to the condensation of
the massive graviton mode using Ricci-Cotton flow, which is the appropriate
generalization of Ricci flow to TMG. When the Chern-Simons coupling is small
the AdS solution flows to warped AdS by the condensation of the massive
graviton mode. When the coupling is large the situation is reversed, and warped
AdS flows to AdS. Minisuperspace models are constructed where these flows are
studied explicitly
Greybody Factors and Charges in Kerr/CFT
We compute greybody factors for near extreme Kerr black holes in D=4 and D=5.
In D=4 we include four charges so that our solutions can be continuously
deformed to the BPS limit. In D=5 we include two independent angular momenta so
Left-Right symmetry is incorporated. We discuss the CFT interpretation of our
emission amplitudes, including the overall frequency dependence and the
dependence on all black hole parameters. We find that all additional parameters
can be incorporated Kerr/CFT, with central charge independent of U(1) charges.Comment: 27 pages. v2: typos fixed, references adde
Yet Another Realization of Kerr/CFT Correspondence
The correspondence between the Kerr black hole and a boundary CFT has been
conjectured recently. The conjecture has been proposed first only for the half
of the CFT, namely for left movers. For right movers, the correspondence has
been also found out through the suitable asymptotic boundary condition.
However, the boundary conditions for these two studies are exclusive to each
other. The boundary condition for left movers does not allow the symmetry of
right movers, and vice versa. We propose new boundary condition which allows
both of left and right movers.Comment: 6 pages, references adde
D-brane Construction of the 5D NHEK Dual
Extremal but non-supersymmetric charged black holes with SU(2)_L spin in IIB
string theory compactified to five dimensions on K^3 x S^1 are considered.
These have a near-horizon or NHEK region with an enhanced SL(2,R)_L conformal
symmetry. It is shown that the NHEK geometry has a second, inequivalent,
asymptotically flat extension in which the radius of the S^1 becomes infinite
but the radius of the angular circles of SU(2)_L orbits approach a constant.
The asymptotic charges associated to the second solution identify it as a 5D
D1-D5-Taub-NUT black string with certain nonzero worldvolume charge densities,
temperatures and chemical potentials. The dual of the NHEK geometry is then
identified as an IR limit of this wrapped brane configuration.Comment: 11 page
Subtracted Geometry From Harrison Transformations
We consider the rotating non-extremal black hole of N=2 D=4 STU supergravity
carrying three magnetic charges and one electric charge. We show that its
subtracted geometry is obtained by applying a specific SO(4,4) Harrison
transformation on the black hole. As previously noted, the resulting subtracted
geometry is a solution of the N=2 S=T=U supergravity.Comment: 11 pages main text; total 24 pages; Latex file; v2 typos corrected +
ref added; v3 results significantly strengthened, changes in section 3.1 and
appendix C, version to appear in JHE
Three-dimensional massive gravity and the bigravity black hole
We study three-dimensional massive gravity formulated as a theory with two
dynamical metrics, like the f-g theories of Isham-Salam and Strathdee. The
action is parity preserving and has no higher derivative terms. The spectrum
contains a single massive graviton. This theory has several features discussed
recently in TMG and NMG. We find warped black holes, a critical point, and
generalized Brown-Henneaux boundary conditions.Comment: 8 pages, Revtex. Minor change. References adde
String Theory on Warped AdS_3 and Virasoro Resonances
We investigate aspects of holographic duals to time-like warped AdS_3
space-times--which include G\"odel's universe--in string theory. Using
worldsheet techniques similar to those that have been applied to AdS_3
backgrounds, we are able to identify space-time symmetry algebras that act on
the dual boundary theory. In particular, we always find at least one Virasoro
algebra with computable central charge. Interestingly, there exists a dense set
of points in the moduli space of these models in which there is actually a
second commuting Virasoro algebra, typically with different central charge than
the first. We analyze the supersymmetry of the backgrounds, finding related
enhancements, and comment on possible interpretations of these results. We also
perform an asymptotic symmetry analysis at the level of supergravity, providing
additional support for the worldsheet analysis.Comment: 24 pages + appendice
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