Exact solutions for gravitational collapse with a dilaton field in arbitrary dimensions

We present time-dependent analytic solutions to the Einstein equations coupled with a dilaton (scalar) field. The background geometry for the solutions is a product of an N-dimensional spherically symmetric space and a d-dimensional flat space. We discuss the global properties of the spacetime.Comment: 15 pages, 2 eps figure

Extremal Black Holes and Strings in Linear Dilaton Vacua

Analytic solutions to low-energy string theory, which describe arbitrary numbers of extreme `black holes (strings)' in linear dilaton vacua, are found.Comment: 11 pages, no figur

More on quantum kinks in gauge theories on R2⊗S1R^2 \otimes S^1

Quantum kinks in gauge theories on $R^2\otimes S^1$ space-time are studied. To obtain the, explicit profile of the kinks, we calculated effective actions including derivative corrections for vacuum gauge fields on $S^1$ at zero, and finite temperature up to one-loop level. It is found that there are soliton solutions in scalar QED. We also find that the derivative correction tends to make the vacuum unstable in $SU(2)$ Yang-Mills theory.Comment: 9 pages, 3 figure

Vacuum polarization around a three-dimensional black hole

We calculate the Euclidean propagator for a conformally coupled massless scalar field in the background of the three-dimensional black hole. The expectation value $\langle\varphi^2\rangle$ in the Hartle-Hawking state is obtained in the spacetime.Comment: 6 pages, 1 figure. typos fixe

Multi-black hole solutions in cosmological Einstein-Maxwell-dilaton theory

Adopting a simple ansatz, we find exact solutions to the Einstein-Maxwell-dilaton equations, which stand for the multi-black hole configuration with maximal charge in a cosmological metric and dilaton field background driven by a cosmological term.Comment: 10 pages, no figure. a typo fixe

Magnetic Moment of Electrons near Cosmic Strings

We study the effect of background geometry generated by a thin cosmic string on the anomalous magnetic moment of the electron. We find that the magnitude of the quantum correction to the magnetic moment depends on the distance from the cosmic string as well as on the deficit angle.Comment: 9 pages, no figur

Motion of Test Particles around a Charged Dilatonic Black Hole

We examine motion of test particles with various masses, electric charges and dilatonic charges in a background metric and fields of a charged dilatonic black hole.Comment: 12 pages, no figur

Vacuum polarization near asymptotically anti-de Sitter black holes in odd dimensions

Recently, Ba\~nados, Teitelboim and Zanelli obtained spherically symmetric black hole solutions in a particular class of Einstein--Lovelock gravity. We derive the propagator in an exact form for a conformal scalar field in the asymptotically anti-de Sitter black hole spacetime so as to study the quantum effects of the scalar fields. We treat the cases in odd dimensions in this paper. We calculate the vacuum expectation value of $\langle\varphi^2\rangle$ and show its dependence on the radial coordinate for the five-dimensional case as an example.Comment: 12 pages, 3 figure

Three-dimensional black holes and solitons in higher-dimensional theories with compactification

Several types of static solutions to Einstein's equations coupled with antisymmetric tensor fields are found in $(2+N+1)$-dimensional spacetime. The solutions describe a product of a three-dimensional radially symmetric spacetime and an internal maximally symmetric manifold. The scale of the internal space may depend on the radial distance from the origin in these solutions.Comment: 8 pages, no figur

Quantum fluctuation of stress tensor and black holes in three dimensions

The quantum stress tensor near a three-dimensional black hole is studied for a conformally coupled scalar field. The back reaction to the metric is also investigated.Comment: 18 pages, 12 figure