287 research outputs found
Global geometry of the 2+1 rotating black hole
The generic rotating BTZ black hole, obtained by identifications in AdS3
space through a discrete subgroup of its isometry group, is investigated within
a Lie theoretical context. This space is found to admit a foliation by
two-dimensional leaves, orbits of a two-parameter subgroup of SL(2,R) and
invariant under the BTZ identification subgroup. A global expression for the
metric is derived, allowing a better understanding of the causal structure of
the black hole.Comment: 9 pages, 1 figur
Holographic Chern-Simons Theories
Chern-Simons theories in three dimensions are topological field theories that
may have a holographic interpretation for suitable chosen gauge groups and
boundary conditions on the fields. Conformal Chern-Simons gravity is a
topological model of 3-dimensional gravity that exhibits Weyl invariance and
allows various holographic descriptions, including Anti-de Sitter, Lobachevsky
and flat space holography. The same model also allows to address some aspects
that arise in higher spin gravity in a considerably simplified setup, since
both types of models have gauge symmetries other than diffeomorphisms. In these
lectures we summarize briefly recent results.Comment: 20 pp, invited lectures prepared for the 7th Aegean Summer School
"Beyond Einstein's Theory of Gravity", 201
Supersymmetric G\"odel and warped black holes in string theory
It is observed that three-dimensional G\"odel black holes can be promoted to
exact string theory backgrounds through an orbifold of an hyperbolic asymmetric
marginal deformation of the SL(2,R) WZW model. Tachyons are found in the
spectrum of long strings. Uplifting these solutions in type IIB supergravity,
extremal black holes are shown to preserve one supersymmetry in accordance with
the BTZ limit. We also make connections with some recently discussed warped
black hole solutions of topologically massive gravity, showing that they
actually correspond to quotients of spacelike squashed AdS_3.Comment: 15 page
The Fuzzy Sphere: From The Uncertainty Relation To The Stereographic Projection
On the fuzzy sphere, no state saturates simultaneously all the Heisenberg
uncertainties. We propose a weaker uncertainty for which this holds. The family
of states so obtained is physically motivated because it encodes information
about positions in this fuzzy context. In particular, these states realize in a
natural way a deformation of the stereographic projection. Surprisingly, in the
large limit, they reproduce some properties of the ordinary coherent states
on the non commutative plane.Comment: 18 pages, Latex. Minor changes in notations. Version to appear in
JHE
Three-dimensional black holes from deformed anti-de Sitter
We present new exact three-dimensional black-string backgrounds, which
contain both NS--NS and electromagnetic fields, and generalize the BTZ black
holes and the black string studied by Horne and Horowitz. They are obtained as
deformations of the Sl(2,R) WZW model. Black holes resulting from purely
continuous deformations possess true curvature singularities. When discrete
identifications are introduced, extra chronological singularities appear, which
under certain circumstances turn out to be naked. The backgrounds at hand
appear in the moduli space of the Sl(2,R) WZW model. Hence, they provide exact
string backgrounds and allow for a more algebraical CFT description. This makes
possible the determination of the spectrum of primaries.Comment: JHEP style, 33 pages, 1 figur
Absorption cross section in the topologically massive gravity at the critical point
The absorption cross section for the the warped AdS black hole background
shows that it is larger than the area even if the s-wave limit is considered.
It raises some question whether the deviation from the areal cross section is
due to the warped configuration of the geometry or the rotating coordinate
system, where these two effects are mixed up in the warped AdS black hole.
So, we study the low-frequency scattering dynamics of propagating scalar fields
under the warped AdS background at the critical point which reduces to the
BTZ black hole in the rotating frame without the warped factor, which shows
that the deformation effect at the critical point does not appear.Comment: 12 pages, LaTe
The Spectrum of Strings on Warped AdS_3 x S^3
String theory on NS-NS AdS_3 x S^3 admits an exactly marginal deformation
which breaks the SL(2,R)_R x SL(2,R)_L isometry of AdS_3 down to SL(2,R)_R x
U(1)_L. The holographic dual is an exotic and only partially understood type of
two-dimensional CFT with a reduced unbroken global conformal symmetry group. In
this paper we study the deformed theory on the string worldsheet. It is found
to be related by a spectral flow which is nonlocal in spacetime to the
undeformed worldsheet theory. An exact formula for the spectrum of massive
strings is presented.Comment: 26 pages, no figure
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