Three-dimensional black holes and string theory

The exact decay rate for emission of massless minimally coupled scalar fields by a non-extremal black hole in 2 + 1 dimensions is obtained. At low energy, the decay rate into scalars with zero angular momentum is correctly reproduced within conformal field theory. The conformal field theory has both left- and right-moving sectors and their contribution to the decay rate is associated naturally with left and right temperatures of the black hole.