Deformation of Dirac operators along orbits and quantization of noncompact Hamiltonian torus manifolds

Abstract

We give a formulation of a deformation of Dirac operator along orbits of a group action on a possibly non-compact manifold to get an equivariant index and a K-homology cycle representing the index. We apply this framework to non-compact Hamiltonian torus manifolds to define geometric quantization from the view point of index theory. We give two applications. The first one is a proof of a [Q,R]=0 type theorem, which can be regarded as a proof of the Vergne conjecture for Abelian case. The other is a Danilov-type formula for toric case in the non-compact setting, which a localization phenomenon of geometric quantization in the non-compact setting. The proofs are based on the localization of index to lattice points.