Heat kernels and the range of the trace on completions of twisted group algebras

Abstract

Heat kernels are used in this paper to express the analytic index of projectively invariant Dirac type operators on G-covering spaces of compact manifolds, as elements in the K-theory of certain unconditional completions of the twisted group algebra of G. This is combined with V. Lafforgue's results in the untwisted case, to compute the range of the trace on the K-theory of these algebras, under the hypothesis that G is in the class C' (defined by V. Lafforgue).