Comments on the Gauge Fixed BRST Cohomology and the Quantum Noether Method

Abstract

We discuss in detail the relation between the gauge fixed and gauge invariant BRST cohomology. We showed previously that in certain gauges some cohomology classes of the gauge-fixed BRST differential do not correspond to gauge invariant observables. We now show that in addition ``accidental'' conserved currents may appear. These correspond one-to-one to observables that become trivial in this gauge. We explicitly show how the gauge-fixed BRST cohomology appears in the context of the Quantum Noether Method.

Comments: 24 pages, example section improved, short version without background material will appear in Physics Letters B