Canonical Quantisation in n.A=0 gauges

TL;DR

This paper provides a unified derivation of the propagator in gauges where n·A=0, applicable to timelike, spacelike, and lightlike n, and discusses related physical states and issues.

Contribution

It offers a comprehensive derivation of the propagator in n·A=0 gauges covering all cases of n's nature, clarifying physical state conditions.

Findings

Unified derivation of propagator for all n·A=0 gauges

Analysis of physical states in different gauge cases

Clarification of physical questions related to these gauges

Abstract

We give a unified derivation of the propagator in the gauges $n.A=0$ for $n^2$ timelike, spacelike or lightlike. We discuss the physical states and other physical questions.