A new class of examples of group-valued moment maps

Abstract

The purpose of this paper is to construct new examples of group-valued moment maps. As the main tool for construction of such examples we use quasi-symplectic implosion which was introduced in [HJS06]. More precisely we show that there are certain strata of $D\mathbf{Sp}(n{)}_{\mathrm{impl}}$, the universal imploded space, where it is singular but whose closure is a smooth quasi-Hamiltonian $\mathbf{Sp}(n)\times T$ space.

12 pages