ON THE GENERAL STRUCTURE OF GAUGED WESS-ZUMINO-WITTEN TERMS

The problem of gauging a closed form is considered. When the target ma nifold is a simple Lie group G, it is seen that there is no obstructio n to the gauging of a subgroup H subset of G if we may construct from the form a cocycle for the relative Lie algebra cohomology (or for the equivariant cohomology), and an explicit general expression for these cocycles is given. The common geometrical structure of the gauged clo sed forms and the D'Hoker and Weinberg effective actions of WZW type, as well as the obstructions for their existence, is also exhibited and explained. (C) 1998 Elsevier Science B.V.