Infraparticle quantum fields and the formation of photon clouds

TL;DR

This paper introduces an exactly solvable quantum field model that captures key infrared phenomena of QED, such as photon clouds and infraparticles, providing a new framework for understanding massless gauge theories.

Contribution

It presents a non-perturbative, solvable model of a dressed Dirac field that reproduces QED's infrared features and offers a new approach towards full, off-shell QED formulation.

Findings

Model exhibits photon clouds and infraparticle behavior

Reproduces key features of QED's infrared structure

Provides a basis for new scattering theories with massless particles

Abstract

A non-perturbative and exactly solvable quantum field theoretical model for a "dressed Dirac field" is presented, that exhibits all the kinematical features of QED: an appropriate delocalization of the charged field as a prerequisite for the global Gauss Law, superselected photon clouds (asymptotic expectation values of the Maxwell field), infraparticle nature of charged particles that cannot be separated from their photon clouds, broken Lorentz symmetry. The model serves as an intermediate leg on a new roadmap towards full QED, formulated as an off-shell theory, i.e., including a perturbative construction of its interacting charged fields. It also fills a gap in recent discussions of the "Infrared Triangle", and points the way towards a new scattering theory for theories with massless particles of helicity $\geq 1$, in which infraparticles can be described at the level of charged fields, rather than just states.