Topological Gauged WZW Models and 2D Gravity

We study the "topological gauged WZW model associated with $SU(2)/U(1)$",which is defined as the twisted version of the corresponding supersymmetric gauged WZW model. It is shown that this model is equivalent to a topological conformal field theory characterized by two independent topological conformal algebras, one of which is the "twisted Kazama-Suzuki type" and the other is "twisted Coulomb gas type". We further show that our formalism of this gauged WZW model naturally reduces to the well-known formulations of 2D gravity coupled with conformal matter; one of the gauge choices leads to the K.Li's theory, and the alternative choices lead to the KPZ theory or the DDK (Liouville) theory.Comment: 36pages, LATEX FIL