7,568 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
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
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
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
Can the string scale be related to the cosmic baryon asymmetry?
In a previous work, a mechanism was presented by which baryon asymmetry can
be generated during inflation from elliptically polarized gravitons.
Nonetheless, the mechanism only generated a realistic baryon asymmetry under
special circumstances which requires an enhancement of the lepton number from
an unspecified GUT. In this note we provide a stringy embedding of this
mechanism through the Green-Schwarz mechanism, demonstrating that if the
model-independent axion is the source of the gravitational waves responsible
for the lepton asymmetry, one can observationally constrain the string scale
and coupling.Comment: 12 Pages, typo corrected in the tex
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