56 research outputs found
On Classification of Geometries with SO(2,2) Symmetry
Motivated by the Extremal Vanishing Horizon (EVH) black holes, their near
horizon geometry and the EVH/CFT proposal, we construct and classify solutions
with (local) SO(2,2) symmetry to four and five dimensional
Einstein-Maxwell-Dilaton (EMD) theory with positive, zero or negative
cosmological constant Lambda, the EMD- theory, and also
gauged supergravity in four dimensions and gauged supergravity in five
dimensions. In four dimensions the geometries are warped product of AdS3 with
an interval or a circle. In five dimensions the geometries are of the form of
warped product of AdS3 and a 2d surface . For the
Einsten-Maxwell- theory we prove that should have a U(1)
isometry, a rigidity theorem in this class of solutions. We also construct all
d dimensional Einstein vacuum solutions with or
isometry.Comment: 26 pages, updated to published versio
Non-Supersymmetric Attractors in BI black holes
We study attractor mechanism in extremal black holes of Einstein-Born-Infeld
theories in four dimensions. We look for solutions which are regular near the
horizon and show that they exist and enjoy the attractor behavior. The
attractor point is determined by extremization of the effective potential at
the horizon. This analysis includes the backreaction and supports the validity
of non-supersymmetric attractors in the presence of higher derivative
interactions in the gauge field part.Comment: 15 pages, minor corrections, references adde
Near Horizon Structure of Extremal Vanishing Horizon Black Holes
We study the near horizon structure of Extremal Vanishing Horizon (EVH) black
holes, extremal black holes with vanishing horizon area with a vanishing
one-cycle on the horizon. We construct the most general near horizon EVH and
near-EVH ansatz for the metric and other fields, like dilaton and gauge fields
which may be present in the theory. We prove that (1) the near horizon EVH
geometry for generic gravity theory in generic dimension has a three
dimensional maximally symmetric subspace; (2) if the matter fields of the
theory satisfy strong energy condition either this 3d part is AdS, or the
solution is a direct product of a locally 3d flat space and a dimensional
part; (3) these results extend to the near horizon geometry of near-EVH black
holes, for which the AdS part is replaced with BTZ geometry. We present
some specific near horizon EVH geometries in 3, 4 and 5 dimensions for which
there is a classification. We also briefly discuss implications of these
generic results for generic (gauged) supergravity theories and also for the
thermodynamics of near-EVH black holes and the EVH/CFT proposal.Comment: 26 page
Three Theorems on Near Horizon Extremal Vanishing Horizon Geometries
EVH black holes are Extremal black holes with Vanishing Horizon area, where
vanishing of horizon area is a result of having a vanishing one-cycle on the
horizon. We prove three theorems regarding near horizon geometry of EVH black
hole solutions to generic Einstein gravity theories in diverse dimensions.
These generic gravity theories are Einstein-Maxwell-dilaton-Lambda theories,
and gauged or ungauged supergravity theories with U(1) Maxwell fields. Our
three theorems are: (1) The near horizon geometry of any EVH black hole has a
three dimensional maximally symmetric subspace. (2) If the energy momentum
tensor of the theory satisfies strong energy condition either this 3d part is
an AdS3, or the solution is a direct product of a locally 3d flat space and a
d-3 dimensional part. (3) These results extend to the near horizon geometry of
near-EVH black holes, for which the AdS3 part is replaced with BTZ geometry.Comment: 5 page
Yang-Baxter Deformations Beyond Coset Spaces (a slick way to do TsT)
Yang-Baxter string sigma-models provide a systematic way to deform coset
geometries, such as , while retaining the -model
integrability. It has been shown that the Yang-Baxter deformation in target
space is simply an open-closed string map that can be defined for any geometry,
not just coset spaces. Given a geometry with an isometry group and a bivector
that is assumed to be a linear combination of antisymmetric products of Killing
vectors, we show the equations of motion of (generalized) supergravity reduce
to the Classical Yang-Baxter Equation associated with the isometry group,
proving the statement made in [1]. These results bring us closer to the proof
of the "YB solution generating technique" for (generalized) supergravity
advertised in [1] and in particular provide an economical way to perform TsT
transformations.Comment: 33 pages; v2 typos fixed and reference added; v3 further improvements
in text, matches published version; v4 typo in expression for B (4.9)
correcte
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