Dijkgraaf-Witten invariants of surfaces and projective representations of groups
arXiv:0706.0160 · doi:10.1016/j.geomphys.2007.08.009
Abstract
We compute the Dijkgraaf-Witten invariants of surfaces in terms of projective representations of groups. As an application we prove that the complex Dijkgraaf-Witten invariants of surfaces of positive genus are positive integers.
second version: a mistake corrected in the non-orientable case and a few improvements added