2D gravity and the black hole solution in 2D critical string theory

Abstract

We discuss the relation between 2D gravity and critical string theory in two target space dimensions. In particular we consider the effect that the tachyon, and its back reaction on the metric, has on the interpretation of the critical theory as a non-critical theory coupled to world sheet gravity. We examine the generalizations of the black hole solution of the critical theory and argue that a generic feature of these solutions is that they have two horizons, similar to, but distinct from, the Reissner-Nordstrøm black hole. We also find some indication that the tachyon may destabilize a naked singularity. Finally we show that KPZ scaling is valid for the general solution of the critical theory, when it is interpreted as a theory of world sheet gravity.