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

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

Hole spin relaxation in [001] strained asymmetric Si/SiGe and Ge/SiGe quantum wells

Hole spin relaxation in [001] strained asymmetric Si/Si$_{0.7}$Ge$_{0.3}$ (Ge/Si$_{0.3}$Ge$_{0.7}$) quantum wells is investigated in the situation with only the lowest hole subband being relevant. The effective Hamiltonian of the lowest hole subband is obtained by the subband L\"owdin perturbation method in the framework of the six-band Luttinger ${\bf k}\cdot{\bf p}$ model, with sufficient basis functions included. The lowest hole subband in Si/SiGe quantum wells is light-hole like with the Rashba spin-orbit coupling term depending on momentum both linearly and cubically, while that in Ge/SiGe quantum wells is a heavy hole state with the Rashba spin-orbit coupling term depending on momentum only cubically. The hole spin relaxation is investigated by means of the fully microscopic kinetic spin Bloch equation approach, with all the relevant scatterings considered. It is found that the hole-phonon scattering is very weak, which makes the hole-hole Coulomb scattering become very important. The hole system in Si/SiGe quantum wells is generally in the strong scattering limit, while that in Ge/SiGe quantum wells can be in either the strong or the weak scattering limit. The Coulomb scattering leads to a peak in both the temperature and hole density dependences of spin relaxation time in Si/SiGe quantum wells, located around the crossover between the degenerate and nondegenerate regimes. Nevertheless, the Coulomb scattering leads to not only a peak but also a valley in the temperature dependence of spin relaxation time in Ge/SiGe quantum wells.... (The remaining is omitted due to the limit of space).Comment: 12 pages, 11 figures, PRB in pres

Spin diffusion/transport in nn-type GaAs quantum wells

The spin diffusion/transport in $n$-type (001) GaAs quantum well at high temperatures ($\ge120$ K) is studied by setting up and numerically solving the kinetic spin Bloch equations together with the Poisson equation self-consistently. All the scattering, especially the electron-electron Coulomb scattering, is explicitly included and solved in the theory. This enables us to study the system far away from the equilibrium, such as the hot-electron effect induced by the external electric field parallel to the quantum well. We find that the spin polarization/coherence oscillates along the transport direction even when there is no external magnetic field. We show that when the scattering is strong enough, electron spins with different momentums oscillate in the same phase which leads to equal transversal spin injection length and ensemble transversal injection length. It is also shown that the intrinsic scattering is already strong enough for such a phenomena. The oscillation period is almost independent on the external electric field which is in agreement with the latest experiment in bulk system at very low temperature [Europhys. Lett. {\bf 75}, 597 (2006)]. The spin relaxation/dephasing along the diffusion/transport can be well understood by the inhomogeneous broadening, which is caused by the momentum-dependent diffusion and the spin-orbit coupling, and the scattering. The scattering, temperature, quantum well width and external magnetic/electric field dependence of the spin diffusion is studied in detail.Comment: 12 pages, 6 figures, to be published in J Appl. Phy

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

The cucumber long hypocotyl mutant lacks a light-stable PHYB-like phytochrome

A novel cDNA sequence homologous to a phytochrome B (phyB) gene that was isolated in a library from tobacco tissue has been used in an Escherichia coli expression system to raise anti-phytochrome B (anti-PHYB) polypeptide-specific monoclonal antibodies. The specificity of these antibodies has been tested by cross-reactivity against purified pea light-labile type 1 and light-stable type 2 phytochromes, with some antibodies reacting with the type 2 and none with the type 1 phytochromes. One such antibody, monoclonal mAT1, has been employed to analyze the phytochrome molecular species present in a photomorphogenic long hypocotyl (lh) mutant of cucumber. The results indicated that the mutant contains wild-type levels of the light-labile type 1 phytochrome polypeptide (PHYA), which has an apparent molecular mass of approximately 120 kD, but shows less than 1% (detection limit) of a light-stable polypeptide recognized by mAT1 in wild-type seedlings. This protein, not detectable in the lh mutant, has the properties of light-stable type 2 phytochrome, has an apparent molecular mass of 116 to 117 kD, and remains at constant levels under continuous low-fluence-rate red light. Therefore, we conclude that the lh mutant lacks at least one type 2 phytochrome-like polypeptide, most probably a phyB gene product. The correlation between the lack of this protein and the deficiency or absence of physiological responses to a light-stable phytochrome species in this mutant helps to identify the physiological roles played by the products of different subfamilies within the phytochrome gene family

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, $P$. 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

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