987 research outputs found
Index theory and dynamical symmetry enhancement of M-horizons
We show that near-horizon geometries of 11-dimensional supergravity preserve
an even number of supersymmetries. The proof follows from Lichnerowicz type
theorems for two horizon Dirac operators, the field equations and Bianchi
identities, and the vanishing of the index of a Dirac operator on the
9-dimensional horizon sections. As a consequence of this, we also prove that
all M-horizons with non-vanishing fluxes admit a sl(2,R) subalgebra of
symmetries.Comment: Minor typos corrected. 22 pages, latex. Repeats equations and
descriptions from arXiv:1207.708
On supersymmetric AdS6 solutions in 10 and 11 dimensions
We prove a non-existence theorem for smooth, supersymmetric, warped AdS6
solutions with connected, compact without boundary internal space in D=11 and
(massive) IIA supergravities. In IIB supergravity we show that if such AdS6
solutions exist, then the NSNS and RR 3-form fluxes must be linearly
independent and certain spinor bi-linears must be appropriately restricted.
Moreover we demonstrate that the internal space admits an so(3) action which
leaves all the fields invariant and for smooth solutions the principal orbits
must have co-dimension two. We also describe the topology and geometry of
internal spaces that admit such a so(3) action and show that there are no
solutions for which the internal space has topology F * S^2, where F is an
oriented surface.Comment: 26 pages, late
Gravitational Instantons and Euclidean Supersymmetry
Supersymmetric instanton solutions in four dimensional Euclidean ungauged
Einstein-Maxwell theory are analysed and classified according to the fraction
of supersymmetry they preserve, using spinorial geometry techniques.Comment: 10 pages, late
Concentric Black Rings
We present new supersymmetric solutions of five-dimensional minimal
supergravity that describe concentric black rings with an optional black hole
at the common centre. Configurations of two black rings are found which have
the same conserved charges as a single rotating black hole; these black rings
can have a total horizon area less than, equal to, or greater than the black
hole with the same charges. A numerical investigation of these particular black
ring solutions suggests that they do not have closed timelike curves.Comment: 7 pages, minor alterations, typos corrected. Version to be published
in PR
On Non-extremal Instantons and Black Holes
We consider a general analysis and a specific ansatz for the study of
non-supersymmetric solutions in arbitrary dimensions and various metric
signatures. In all cases, we find that the conditions on the solutions can be
written in terms of quadratic forms involving the gauge coupling of the theory
and constants of integration associated with the scalar fields. Depending on
the signature of the metric, our analysis should provide a general framework
for finding non-extremal black holes, instantons, branes and S-branes.Comment: 19 page
Null Half-Supersymmetric Solutions in Five-Dimensional Supergravity
We classify half-supersymmetric solutions of gauged N=2, D=5 supergravity
coupled to an arbitrary number of abelian vector multiplets for which all of
the Killing spinors generate null Killing vectors. We show that there are four
classes of solutions, and in each class we find the metric, scalars and gauge
field strengths. When the scalar manifold is symmetric, the solutions
correspond to a class of local near horizon geometries recently found by
Kunduri and Lucietti.Comment: 46 pages, typos corrected and reference added. Section 7.1 has been
added: it is shown that the solutions found here correspond to a class of
solutions found in arXiv:0708.3695. Uses JHEP3.cl
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