Norm-square localization for Hamiltonian $LG$-spaces

Abstract

We prove a formula for twisted Duistermaat-Heckman distributions associated to a Hamiltonian $LG$-space. The terms of the formula are localized at the critical points of the norm-square of the moment map, and can be computed in cross-sections. Our main tools are the theory of quasi-Hamiltonian $G$-spaces, as well as the Hamiltonian cobordism approach to norm-square localization introduced recently by Harada and Karshon.