Loops and polarization in strong-field QED

TL;DR

This paper develops practical approximations for Mueller matrices in strong-field QED, enabling analysis of polarization and spin effects in arbitrary laser fields and particle states, including loop contributions.

Contribution

It introduces new approximations of Mueller matrices in locally-constant and monochromatic regimes for arbitrary polarization, accounting for loop effects.

Findings

Derived Mueller matrices for various regimes and polarizations

Included effects of loop contributions on spin and polarization

Applicable to arbitrary laser shapes and particle states

Abstract

In a previous paper we showed how higher-order strong-field-QED processes in long laser pulses can be approximated by multiplying sequences of "strong-field Mueller matrices". We obtained expressions that are valid for arbitrary field shape and polarization. In this paper we derive practical approximations of these Mueller matrices in the locally-constant- and the locally-monochromatic-field regimes. We allow for arbitrary laser polarization as well as arbitrarily polarized initial and final particles. The spin and polarization can also change due to loop contributions (the mass operator for electrons and the polarization operator for photons). We derive Mueller matrices for these as well.