Symplectic quotients by a nonabelian group and by its maximal torus
Abstract
Description
This paper examines the relationship between the symplectic quotient X//G of a Hamiltonian G-manifold X, and the associated symplectic quotient X//T, where T is a maximal torus, in the case in which X//G is a compact manifold or orbifold.
The three main results are: a formula expressing the rational cohomology ring of X//G in terms of the rational cohomology ring of X//T; an `integration' formula, which expresses cohomology pairings on X//G in terms of cohomology pairings on X//T; and an index formula, which expresses the indices of elliptic operators on X//G in terms of indices on X//T.
(The results of this paper are complemented by the results in a companion paper, in which different techniques are used to derive formulae for cohomology pairings on symplectic quotients X//T, where T is a torus, in terms of the T-fixed points of X. That paper also gives some applications of the formulae proved here.)
18 pages, latex2e. Submitted to Annals of Mathematics Mar 99, accepted for publication Dec 99
18 pages, latex2e. Submitted to Annals of Mathematics Mar 99, accepted for publication Dec 99