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

TL;DR

This paper explores the relationship between gauge-fixed and gauge-invariant BRST cohomology, revealing that certain conserved currents are gauge-dependent and illustrating their role within the Quantum Noether Method.

Contribution

It clarifies the connection between gauge-fixed and gauge-invariant BRST cohomology and introduces the concept of accidental conserved currents in specific gauges.

Findings

Some cohomology classes do not correspond to gauge-invariant observables.

Accidental conserved currents can appear in certain gauges.

Gauge-fixed BRST cohomology is linked to 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.