An index for gauge-invariant operators and the Dixmier-Douady invariant

Victor Nistor, Evgenij Troitsky

Let $\GR \to B$ be a bundle of compact Lie groups acting on a fiber bundle $Y\to B$. In this paper we introduce and study gauge-equivariant $K$-theory groups $K_\GR^i(Y)$. These g…