BLACK-HOLE PHYSICS AND LIOUVILLE THEORY

Hamiltonian path integral quantization of the SO(2, 1)/SO(2) and SO(2, 1)/SO(1, 1) gauged WZW models is considered. The SO(2, 1)/SO(2) model yields the Liouville theory coupled to a free scalar field after eliminating the group coordinates in favor of their conjugate momenta. The SO(2, 1)/SO(1, 1) model, recently argued to be a two-dimensional black-hole solution to string theory, can also be studied in momentum space. The resulting negative-metric Liouville-like theory has indefinite cosmological constant, is coupled to a positive-metric free scalar field, and lives on a Minkowski world sheet. The scaling variable \mu\ of Liouville theory is related to the mass of the black hole. The connection to Liouville theory should provide the exact solution for correlation functions in the euclidean black-hole geometry using matrix models and Liouville theory; for the Lorentz-signature Schwarzschild geometry it gives us a tool to investigate the properties of singularities in string theory.