Orbifold quantum cohomology of the classifying space of a finite group

Abstract

We work through, in detail, the orbifold quantum cohomology, with gravitational descendants, of the stack BG, the point modulo trivial action of a finite group G. We provide a simple description of algebraic structures on the state space of this theory. As a consequence, we find that multiple copies of commuting Virasoro algebras appear in this theory which completely determine the correlators of the theory.

For the Proceedings of the ``Mathematical Aspects of Orbifold String Theory'' conference in Madison, Wisconsin, May, 2001