Faddev-Popov gauge fixing

Abstract

This talk is a continuation of the previous presentation where Feynman diagrams were introduced in a simple setting of rapidly oscillating integrals. This time I will assume that the measure and the function which is integrated are invariant under the action of a Lie group(think of unitary or orthogonal matrices). In this case the integral can be computed in two different ways in terms of two different Feynman diagrams. Algebraic proof that these two ways of computing a rapidly oscillating integral gives the same answer is still an open problem.