The Dijkgraaf-Witten invariants from second Chern classes

Abstract

Given a 3-cocycle $\psi$ in the cohomology of a finite group $G$, we can define the Dijkgraaf-Witten invariant of closed 3-manifolds. In this paper, we focus on the case where $\psi$ is a 3-cocycle canonically obtained from the second Chern class of a representation of $G$, and show some procedures for computing the invariant, and clarify its topological interpretation under some conditions.

arXiv comment11 pages and no figure. I revised several minor errors. To appear the Mathematical Journal of Okayama University