1,060 research outputs found
Near-horizon geometries of supersymmetric AdS(5) black holes
We provide a classification of near-horizon geometries of supersymmetric,
asymptotically anti-de Sitter, black holes of five-dimensional U(1)^3-gauged
supergravity which admit two rotational symmetries. We find three
possibilities: a topologically spherical horizon, an S^1 \times S^2 horizon and
a toroidal horizon. The near-horizon geometry of the topologically spherical
case turns out to be that of the most general known supersymmetric,
asymptotically anti-de Sitter, black hole of U(1)^3-gauged supergravity. The
other two cases have constant scalars and only exist in particular regions of
this moduli space -- in particular they do not exist within minimal gauged
supergravity. We also find a solution corresponding to the near-horizon
geometry of a three-charge supersymmetric black ring held in equilibrium by a
conical singularity; when lifted to type IIB supergravity this solution can be
made regular, resulting in a discrete family of warped AdS(3) geometries.
Analogous results are presented in U(1)^n gauged supergravity.Comment: Latex, 29 pages. v2: minor improvements, references adde
HKT Geometry and Fake Five Dimensional Supergravity
Recent results on the relation between hyper-Kahler geometry with torsion and
solutions admitting Killing spinors in minimal de sitter supergravity are
extended to more general supergravity models with vector multiplets.Comment: 14 pages, latex. Minor typos corrected, references adde
Do supersymmetric anti-de Sitter black rings exist?
We determine the most general near-horizon geometry of a supersymmetric,
asymptotically anti-de Sitter, black hole solution of five-dimensional minimal
gauged supergravity that admits two rotational symmetries. The near-horizon
geometry is that of the supersymmetric, topologically spherical, black hole
solution of Chong et al. This proves that regular supersymmetric anti-de Sitter
black rings with two rotational symmetries do not exist in minimal
supergravity. However, we do find a solution corresponding to the near-horizon
geometry of a supersymmetric black ring held in equilibrium by a conical
singularity, which suggests that nonsupersymmetric anti-de Sitter black rings
may exist but cannot be "balanced" in the supersymmetric limit.Comment: Latex, 18 pages, 1 figure. v2: minor change
Vanishing Preons in the Fifth Dimension
We examine supersymmetric solutions of N=2, D=5 gauged supergravity coupled
to an arbitrary number of abelian vector multiplets using the spinorial
geometry method. By making use of methods developed in hep-th/0606049 to
analyse preons in type IIB supergravity, we show that there are no solutions
preserving exactly 3/4 of the supersymmetry.Comment: 19 pages, latex. Reference added, and further modification to the
introductio
Fast, Preisach-like characterization of hysteretic systems
Proposed is a substantially simplified, Preisach-like model for
characterization of hysteretic systems, in particular magnetic systems. The
main idea is to replace a two-dimensional Preisach density with just two real
functions, describing in a {\em unique way} the reversible and irreversible
processes. As a byproduct of our model we prove, that the major hysteresis loop
alone is insufficient to produce the unique Preisach map. Keywords: magnetic
hysteresis; magnetization processes; materials testing; modeling.Comment: 7 double spaced pages, 4 figures. Presented at 5th International
Symposium on Hysteresis and Micromagnetic Modeling, Budapest, Hungary, May
30th - June 1st, 200
Mapping the G-structures and supersymmetric vacua of five-dimensional N=4 supergravity
We classify the supersymmetric vacua of N=4, d=5 supergravity in terms of
G-structures. We identify three classes of solutions: with R^3, SU(2) and
generic SO(4) structure. Using the Killing spinor equations, we fully
characterize the first two classes and partially solve the latter. With the N=4
graviton multiplet decomposed in terms of N=2 multiplets: the graviton, vector
and gravitino multiplets, we obtain new supersymmetric solutions corresponding
to turning on fields in the gravitino multiplet. These vacua are described in
terms of an SO(5) vector sigma-model coupled with gravity, in three or four
dimensions. A new feature of these N=4 vacua, which is not seen from an N=2
point of view, is the possibility for preserving more exotic fractions of
supersymmetry. We give a few concrete examples of these new supersymmetric
(albeit singular) solutions. Additionally, we show how by truncating the N=4,
d=5 set of fields to minimal supergravity coupled with one vector multiplet we
recover the known two-charge solutions.Comment: 31 pages, late
Isometries of Half Supersymmetric Time-Like Solutions In Five Dimensions
Spinorial geometry techniques have recently been used to classify all half
supersymmetric solutions in gauged five dimensional supergravity with vector
multiplets. In this paper we consider solutions for which at least one of the
Killing spinors generates a timelike Killing vector. We obtain coordinate
transformations which considerably simplify the solutions, and in a number of
cases, we obtain explicitly some additional Killing vectors which were hidden
in the original analysis.Comment: 18 pages, typos corrected, late
Maximally Minimal Preons in Four Dimensions
Killing spinors of N=2, D=4 supergravity are examined using the spinorial
geometry method, in which spinors are written as differential forms. By making
use of methods developed in hep-th/0606049 to analyze preons in type IIB
supergravity, we show that there are no simply connected solutions preserving
exactly 3/4 of the supersymmetry.Comment: 18 pages. References added, comments added discussing the possibility
of discrete quotients of AdS(4) preserving 3/4 supersymmetry
On a class of 4D Kahler bases and AdS_5 supersymmetric Black Holes
We construct a class of toric Kahler manifolds, M_4, of real dimension four,
a subset of which corresponds to the Kahler bases of all known 5D
asymptotically AdS_5 supersymmetric black-holes. In a certain limit, these
Kahler spaces take the form of cones over Sasaki spaces, which, in turn, are
fibrations over toric manifolds of real dimension two. The metric on M_4 is
completely determined by a single function H(x), which is the conformal factor
of the two dimensional space. We study the solutions of minimal five
dimensional gauged supergravity having this class of Kahler spaces as base and
show that in order to generate a five dimensional solution H(x) must obey a
simple sixth order differential equation. We discuss the solutions in detail,
which include all known asymptotically AdS_5 black holes as well as other
spacetimes with non-compact horizons. Moreover we find an infinite number of
supersymmetric deformations of these spacetimes with less spatial isometries
than the base space. These deformations vanish at the horizon, but become
relevant asymptotically.Comment: 34 pages, 3 figures. v2: formula (8.35) and other minor typos
corrected; references added; accepted for publication in JHE
Small Horizons
All near horizon geometries of supersymmetric black holes in a N=2, D=5
higher-derivative supergravity theory are classified. Depending on the choice
of near-horizon data we find that either there are no regular horizons, or
horizons exist and the spatial cross-sections of the event horizons are
conformal to a squashed or round S^3, S^1 * S^2, or T^3. If the conformal
factor is constant then the solutions are maximally supersymmetric. If the
conformal factor is not constant, we find that it satisfies a non-linear vortex
equation, and the horizon may admit scalar hair.Comment: 21 pages, latex. Typos corrected and reference adde
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