Frequency scaling law for nonlinear Compton and Thomson scattering: Relevance of spin and polarization effects

TL;DR

This paper introduces a universal frequency scaling law linking nonlinear Compton and Thomson scattering, highlighting the roles of spin and polarization effects in quantum and classical regimes across various pulse durations.

Contribution

It extends previous frequency scaling laws to include spin and polarization effects, unifying classical and quantum descriptions of scattering processes.

Findings

The scaling law applies to both long and short laser pulses.

Spin and polarization effects explain differences between classical and quantum results.

The law is valid for spectral, angular, and temporal distributions.

Abstract

The distributions of Compton and Thomson radiation for a shaped laser pulse colliding with a free electron are calculated in the framework of quantum and classical electrodynamics, respectively. We introduce a scaling law for the Compton and the Thomson frequency distributions which universally applies to long and short incident pulses. Thus, we extend the validity of frequency scaling postulated in previous studies comparing nonlinear Compton and Thomson processes. The scaling law introduced in this paper relates the Compton no-spin flipping process to the Thomson process over nearly the entire spectrum of emitted radiation, including its high-energy portion. By applying the frequency scaling, we identify that both spin and polarization effects are responsible for differences between classical and quantum results. The same frequency scaling applies to angular distributions and to temporal power distributions of emitted radiation, which we illustrate numerically.