Axion-Dilaton Black Holes

Static spherically symmetric asymptotically flat particle-like and black hole solutions are constructed within the SU(2) sector of 4-dimensional heterotic string effective action. They separate topologically distinct Yang-Mills vacua and are qualitatively similar to the Einstein-Yang-Mills spha- lerons and non-abelian black holes discussed recently. New solutions possess quantized values of the dilaton charge.

We study generic Einstein-Maxwell-Kalb-Ramond-dilaton actions, and derive conditions under which they give rise to static, spherically symmetric black hole solutions. We obtain new asymptotically flat and non-flat black hole solutions which are in general electrically and magnetically charged. They have positive definite and finite quasi-local masses. Existing non-rotating black hole solutions (including those appearing in low energy string theory) are recovered in special li...

Dilaton black holes with a pure electric charge are considered in a framework of a grand canonical ensemble near the extreme state. It is shown that there exists such a subset of boundary data that the Hawking temperature smoothly goes to zero to an infinite value of a horizon radius but the horizon area and entropy are finite and differ from zero. In string theory the existence of a horizon in the extreme limit is due to the finiteness of a system only.

In this talk I address some aspects in the recent developments for N=2 black holes in 4 dimensions. I restrict myself on axion-free solutions that can classically be related to intersections of isotropic $D$- or $M$-branes. After reviewing of some classical properties I include corrections coming from a general cubic prepotential. On the heterotic side these are quantum corrections for these black hole solutions. Finally, I discuss a microscopic interpretation of the entropy ...

We study configurations consisting of a pair of non-extremal black holes in four dimensions, both with the same mass, and with charges of the same magnitude but opposite sign---diholes, for short. We present such exact solutions for Einstein-Maxwell theory with arbitrary dilaton coupling, and also solutions to the U(1)^4 theories that arise from compactified string/M-theory. Despite the fact that the solutions are very complicated, physical properties of these black holes, su...

In these lecture notes from Strings `91, I briefly sketch the analogy between two dimensional black holes and the s-wave sector of four dimensional black holes, and the physical interest of the latter, particularly in the magnetically charged case.

We study general black-hole solutions of the low-energy string effective action in arbitrary dimensions using a general metric that can describe them all in a unified way both in the extreme and non-extreme cases. We calculate the mass, temperature and entropy and study which relations amongst the charges and the mass lead to extremality. We find that the temperature always vanishes in the extreme limit and we find that, for a set of n charges (no further reducible by duality...

We present the four-dimensional non-extremal dyonic black hole solution for Einstein-Maxwell-dilaton theory in absence of a scalar potential written in terms of integration constants only. These integration constants must satisfy a set of conditions imposed by the equations of motion. By defining a posteriori the mass $M$ of the black hole and the dilaton charge $\Sigma$, we show how to recover the dyonic black hole solution found by Kallosh et.al. In particular, our analysis...

In this review we try to give a pedagogical introduction to the recent progress in the resolution of old problems of black hole thermodynamics within superstring theory. We start with a brief description of classical black hole dynamics. Then, follow with the consideration of general properties of supersymmetric black holes. We conclude with the review of the statistical explanation of the black hole entropy and string theory description of the black hole evaporation.

New charged solutions describing black holes with squashed horizons in 5D dilaton gravity are presented. The black hole spacetimes are asymptotically locally flat and have a spacial infinity $R\times S^1\hookrightarrow S^2$. The solutions are analyzed and their thermodynamics is discussed by using the counterterm method.