Charges in Gauge Theories

TL;DR

This paper develops a method to construct and interpret charged particles in gauge theories, demonstrating infra-red finiteness and applicability to massless particles, with implications for the standard model.

Contribution

It introduces a new approach to defining charged particles in gauge theories, ensuring infra-red finite Green's functions and extending to massless cases.

Findings

Explicit solutions in Abelian gauge theories.

Infra-red finite on-shell Green's functions at all perturbation orders.

Applicability to massless charged particles and standard model sectors.

Abstract

In this article we investigate charged particles in gauge theories. After reviewing the physical and theoretical problems, a method to construct charged particles is presented. Explicit solutions are found in the Abelian theory and a physical interpretation is given. These solutions and our interpretation of these variables as the true degrees of freedom for charged particles, are then tested in the perturbative domain and are demonstrated to yield infra-red finite, on-shell Green's functions at all orders of perturbation theory. The extension to collinear divergences is studied and it is shown that this method applies to the case of massless charged particles. The application of these constructions to the charged sectors of the standard model is reviewed and we conclude with a discussion of the successes achieved so far in this programme and a list of open questions.