Gaugeon Formalism with BRST Symmetry

TL;DR

This paper develops a BRST symmetric version of Yokoyama's gaugeon formalism for quantum electrodynamics, enabling gauge choices in curved backgrounds and unifying different gauges within a single Hilbert space.

Contribution

It introduces a BRST symmetric gaugeon formalism that generalizes Yokoyama's approach, allowing applications in gravitational backgrounds and unifying gauge choices.

Findings

BRST symmetry replaces Yokoyama's physical conditions

Formalism applicable in curved spacetime backgrounds

Unified Hilbert space for various gauges

Abstract

We provide a BRST symmetric version of Yokoyama's Type I gaugeon formalism for quantum electrodynamics; the similar theory by Izawa can be considered as a BRST symmetrized Type II theory. With the help of the BRST symmetry, Yokoyama's physical subsidiary conditions are replaced by the Kugo-Ojima type condition. As a result, the formalism becomes applicable even in the background gravitational field. We show how the Hilbert spaces of standard formalism in various gauges are embedded in the single Hilbert space of the present formalism. We also give a path integral derivation of the Lagrangian.