Thermodynamics of Dilatonic Black Holes in $n$ Dimensions

Abstract

We present a formalism for studying the thermodynamics of black holes in dilaton gravity. The thermodynamic variables are defined on a quasilocal surface surrounding the black hole system and are obtained from a general class of Lagrangians involving a dilaton. The formalism thus accommodates a large number of possible theories and black hole spacetimes. Many of the thermodynamic quantities are identified from the contribution of the action on the quasilocal boundary. The entropy is found using path integral techniques, and a first law of thermodynamics is obtained. As an illustration, we calculate the thermodynamic quantities for two black hole solutions in $(1+1)$ dimensions: one obtained from a string inspired theory and the other being a Liouville black hole in the ``$R=\kappa T$'' theory with a Liouville field.