8,633 research outputs found
Gravitating BPS Dyons witout a Dilaton
We describe curved-space BPS dyon solutions, the ADM mass of which saturates
the gravitational version of the Bogomol'nyi bound. This generalizes
self-gravitating BPS monopole solutions of Gibbons et al. when there is no
dilaton.Comment: 10 page
Calabi-Yau Black Holes and Enhancement of Supersymmetry in Five Dimensions
BPS electric and magnetic black hole solutions which break half of
supersymmetry in the theory of N=2 five-dimensional supergravity are discussed.
For models which arise as compactifications of M-theory on a Calabi-Yau
manifold, these solutions correspond, respectively, to the two and five branes
wrapping around the homology cycles of the Calabi-Yau compact space. The
electric solutions are reviewed and the magnetic solutions are constructed. The
near-horizon physics of these solutions is examined and in particular the
phenomenon of the enhancement of supersymmetry. The solutions for the
supersymmetric Killing spinor of the near horizon geometry, identified as
and are also given.Comment: 12 pages, Latex file. CAMS/AU
Complex Numbers, Quantum Mechanics and the Beginning of Time
A basic problem in quantizing a field in curved space is the decomposition of
the classical modes in positive and negative frequency. The decomposition is
equivalent to a choice of a complex structure in the space of classical
solutions. In our construction the real tunneling geometries provide the link
between the this complex structure and analytic properties of the classical
solutions in a Riemannian section of space. This is related to the Osterwalder-
Schrader approach to Euclidean field theory.Comment: 27 pages LATEX, UCSBTH-93-0
Killing tensors and a new geometric duality
We present a theorem describing a dual relation between the local geometry of
a space admitting a symmetric second-rank Killing tensor, and the local
geometry of a space with a metric specified by this Killing tensor. The
relation can be generalized to spinning spaces, but only at the expense of
introducing torsion. This introduces new supersymmetries in their geometry.
Interesting examples in four dimensions include the Kerr-Newman metric of
spinning black-holes and self-dual Taub-NUT.Comment: 20 pages (a4), standard LaTeX, no figure
Hidden supersymmetries in supersymmetric quantum mechanics
We discuss the appearance of additional, hidden supersymmetries for simple
0+1 -invariant supersymmetric models and analyse some geometrical
mechanisms that lead to them. It is shown that their existence depends
crucially on the availability of odd order invariant skewsymmetric tensors on
the (generic) compact Lie algebra , and hence on the cohomology
properties of the Lie algebra considered.Comment: Misprints corrected, two refs. added. To appear in NP
The Geometry of Large Causal Diamonds and the No Hair Property of Asymptotically de-Sitter Spacetimes
In a previous paper we obtained formulae for the volume of a causal diamond
or Alexandrov open set whose duration is
short compared with the curvature scale. In the present paper we obtain
asymptotic formulae valid when the point recedes to the future boundary
of an asymptotically de-Sitter spacetime. The volume (at fixed
) remains finite in this limit and is given by the universal formula
plus
corrections (given by a series in ) which begin at order .
The coefficents of the corrections depend on the geometry of . This
behaviour is shown to be consistent with the no-hair property of cosmological
event horizons and with calculations of de-Sitter quasinormal modes in the
literature.Comment: 13 pages, 2 figures, Latex; references adde
Comments on No-Hair Theorems and Stabilty of Blackholes
In the light of recent blackhole solutions inspired by string theory, we
review some old statements on field theoretic hair on blackholes. We also
discuss some stability issues. In particular we argue that the two dimensional
string blackhole solution is semi-classically stable while the naked
singularity is unstable to tachyon fluctuations. Finally we comment on the
relation between the linear dilaton theory and the blackhole solution.Comment: 14 page
HKT and OKT Geometries on Soliton Black Hole Moduli Spaces
We consider Shiraishi's metrics on the moduli space of extreme black holes.
We interpret the simplification in the pattern of N-body interactions that he
observed in terms of the recent picture of black holes in four and five
dimensions as composites, made up of intersecting branes. We then show that the
geometry of the moduli space of a class of black holes in five and nine
dimensions is hyper-K\"ahler with torsion, and octonionic-K\"ahler with
torsion, respectively. For this, we examine the geometry of point particle
models with extended world-line supersymmetry and show that both of the above
geometries arise naturally in this context. In addition, we construct a large
class of hyper-K\"ahler with torsion and octonionic-K\"ahler with torsion
geometries in various dimensions. We also present a brane interpretation of our
results.Comment: pages 55, phyzzx, some more references have been adde
Black Holes and Critical Points in Moduli Space
We study the stabilization of scalars near a supersymmetric black hole
horizon using the equation of motion of a particle moving in a potential and
background metric. When the relevant 4-dimensional theory is described by
special geometry, the generic properties of the critical points of this
potential can be studied. We find that the extremal value of the central charge
provides the minimal value of the BPS mass and of the potential under the
condition that the moduli space metric is positive at the critical point. We
relate these ideas to the Weinhold and Ruppeiner metrics introduced in the
geometric approach to thermodynamics and used for study of critical phenomena.Comment: 19 pages, Late
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