Partition Functions and Stability Criteria of Topological Insulators

Abstract

The non-chiral edge excitations of quantum spin Hall systems and topological insu-lators are described by means of their partition function. The stability of topological phases protected by time-reversal symmetry is rediscussed in this context and put in relation with the existence of discrete anomalies and the lack of modular invariance of the partition function. The Z2 characterization of stable topological insulators is extended to systems with interacting and non-Abelian edge excitations. ar X iv