Gauged WZW Models Via Equivariant Cohomology

The problem of computing systematically the gauge invariant extension of WZW term through equivariant cohomology is addressed. The analysis done by Witten in the two-dimensional case is extended to the four-dimensional ones. While Cartan's model is used to find the anomaly cancelation condition. It is shown that the Weil model is more appropriated to find the gauge invariant extension of the WZW term. In the process we point out that Weil's and Cartan's models are also useful to stress some connections with the abelian anomaly.