Intersection numbers in quasi-Hamiltonian reduced spaces

Abstract

In this paper we prove a residue formula for intersection pairings of reduced spaces of certain quasi-Hamiltonian G-spaces, by constructing the corresponding Hamiltonian G-space. Our argument closely follows the methods of a 1998 paper of the first author and F. Kirwan on intersection numbers in moduli spaces (for G=SU(n)). For the more general class of compact Lie groups treated by Alekseev, Meinrenken and Woodward, we rely on results of Szenes and Brion-Vergne concerning diagonal bases. Our result is a close analogue of the result of Alekseev-Meinrenken-Woodward.