423 research outputs found
Charged Rotating Kaluza-Klein Black Holes Generated by G2(2) Transformation
Applying the G_{2(2)} generating technique for minimal D=5 supergravity to
the Rasheed black hole solution, we present a new rotating charged Kaluza-Klein
black hole solution to the five-dimensional Einstein-Maxwell-Chern-Simons
equations. At infinity, our solution behaves as a four-dimensional flat
spacetime with a compact extra dimension and hence describes a Kaluza-Klein
black hole. In particlar, the extreme solution is non-supersymmetric, which is
contrast to a static case. Our solution has the limits to the asymptotically
flat charged rotating black hole solution and a new charged rotating black
string solution.Comment: 24 page
Topology Change of Coalescing Black Holes on Eguchi-Hanson Space
We construct multi-black hole solutions in the five-dimensional
Einstein-Maxwell theory with a positive cosmological constant on the
Eguchi-Hanson space, which is an asymptotically locally Euclidean space. The
solutions describe the physical process such that two black holes with the
topology of S^3 coalesce into a single black hole with the topology of the lens
space L(2;1)=S^3/Z_2. We discuss how the area of the single black hole after
the coalescence depends on the topology of the horizon.Comment: 10 pages, Some comments are added. to be published as a letter in
Classical and Quantum Gravit
The Black Di-Ring: An Inverse Scattering Construction
We use the inverse scattering method (ISM) to derive concentric
non-supersymmetric black rings. The approach used here is fully
five-dimensional, and has the modest advantage that it generalizes readily to
the construction of more general axi-symmetric solutions.Comment: v3: 2 subsections added, typos fixed, more refs, journal version. v4:
a transcription error in the ADM mass fixe
Charged Black Holes in a Rotating Gross-Perry-Sorkin Monopole Background
We present a new class of stationary charged black hole solutions to
five-dimensional Einstein-Maxwell-Chern-Simons theories. We construct the
solutions by utilizing so called the squashing transformation. At infinity, our
solutions behave as a four-dimensional flat spacetime plus a `circle' and hence
describe a Kaluza-Klein black hole. More precisely, our solutions can be viewed
as a charged rotating black hole in a rotating Gross-Perry-Sorkin monopole
background with the black hole rotation induced from the background rotation.Comment: 25 pages, 6 figure
Supersymmetric Black Rings on Eguchi-Hanson Space
We construct new supersymmetric black ring solutions on the Eguchi-Hanson
base space as solutions of five-dimensional minimal supergravity. The solutions
have the same two angular momentum components and the asymptotic structure on
timeslices is asymptotically locally Euclidean. The S^1-direction of the black
ring is along the equator on a S^2-bolt on the Eguchi-Hanson space. We also
investigate the limit to a black hole, which describes the BMPV black hole with
the topology of the lens space L(2;1)=S^3/Z_2.Comment: 21 page
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
Opposite field septum magnet system for the separation of charged particle beams
Abstract-The Japan Hadron Facility (JHF) accelerator complex comprises a 50-GeV main synchrotron, a 3-GeV rapid-cycling synchrotron, and a 400-MeV linac. The accelerators provide high-intensity, high-energy proton beams for various scientific fields. These high-intensity, high-energy accelerators, especially the 50-GeV main synchrotron, impose tight demands on the injection/extraction septum magnets for a thin structure, large aperture and high operating field. But to manufacture high field septum magnets on the condition of a large aperture is very difficult because of its extraordinarily strong electromagnetic force due to the self-field. To cope with these tight demands, new design concepts of septa are required. An opposite-field septum magnet system is one of the solutions to realize a thin septa or very high-field septum magnets
A Higher Dimensional Stationary Rotating Black Hole Must be Axisymmetric
A key result in the proof of black hole uniqueness in 4-dimensions is that a
stationary black hole that is ``rotating''--i.e., is such that the stationary
Killing field is not everywhere normal to the horizon--must be axisymmetric.
The proof of this result in 4-dimensions relies on the fact that the orbits of
the stationary Killing field on the horizon have the property that they must
return to the same null geodesic generator of the horizon after a certain
period, . This latter property follows, in turn, from the fact that the
cross-sections of the horizon are two-dimensional spheres. However, in
spacetimes of dimension greater than 4, it is no longer true that the orbits of
the stationary Killing field on the horizon must return to the same null
geodesic generator. In this paper, we prove that, nevertheless, a higher
dimensional stationary black hole that is rotating must be axisymmetric. No
assumptions are made concerning the topology of the horizon cross-sections
other than that they are compact. However, we assume that the horizon is
non-degenerate and, as in the 4-dimensional proof, that the spacetime is
analytic.Comment: 24 pages, no figures, v2: footnotes and references added, v3:
numerous minor revision
Relaxation of Electron Spin during High-Field Transport in GaAs Bulk
A semiclassical Monte Carlo approach is adopted to study the multivalley spin
depolarization of drifting electrons in a doped n-type GaAs bulk semiconductor,
in a wide range of lattice temperature ( K) and doping density
(cm). The decay of the initial non-equilibrium spin
polarization of the conduction electrons is investigated as a function of the
amplitude of the driving static electric field, ranging between 0.1 and 6
kV/cm, by considering the spin dynamics of electrons in both the and
the upper valleys of the semiconductor. Doping density considerably affects
spin relaxation at low temperature and weak intensity of the driving electric
field. At high values of the electric field, the strong spin-orbit coupling of
electrons in the -valleys significantly reduces the average spin
polarization lifetime, but, unexpectedly, for field amplitudes greater than 2.5
kV/cm, the spin lifetime increases with the lattice temperature. Our numerical
findings are validated by a good agreement with the available experimental
results and with calculations recently obtained by a different theoretical
approach.Comment: 14 pages, 6 figure
Moduli space of supersymmetric solitons and black holes in five dimensions
We determine all asymptotically flat, supersymmetric and biaxisymmetric
soliton and black hole solutions to five dimensional minimal supergravity. In
particular, we show that the solution must be a multi-centred solution with a
Gibbons-Hawking base. The proof involves combining local constraints from
supersymmetry with global constraints for stationary and biaxisymmetric
spacetimes. This reveals that the horizon topology must be one of S^3, S^1 x
S^2 or a lens space L(p,1), thereby providing a refinement of the allowed
horizon topologies. We construct the general smooth solution for each possible
rod structure. We find a large moduli space of black hole spacetimes with
noncontractible 2-cycles for each of the allowed horizon topologies. In the
absence of a black hole we obtain a classification of the known `bubbling'
soliton spacetimes.Comment: v2: 43 pages, 5 figures, references added, typos fixed, minor
clarifications, expanded discussion of physical parameters. v3: clarified
statement of theorem 4 (results unchanged, update made after publication
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