An amenability-like property of finite energy path and loop groups

Abstract

We show that the groups of finite energy loops and paths (that is, those of Sobolev class $H^1$) with values in a compact connected Lie group, as well as their central extensions, satisfy an amenability-like property: they admit a left-invariant mean on the space of bounded functions uniformly continuous with regard to a left-invariant metric. Every strongly continuous unitary representation $\pi $ of such a group (which we call skew-amenable) has a conjugation-invariant state on $B({\mathcal{H}}_{\pi })$.