First-order strong-field QED processes in a tightly focused laser beam

TL;DR

This paper extends previous work on strong-field QED processes in tightly focused laser beams by analyzing nonlinear Compton scattering, providing analytical expressions and exploring the symmetry with pair production processes.

Contribution

It generalizes earlier results to include non-counterpropagating photons and derives analytical formulas for nonlinear Compton scattering in realistic laser-electron interactions.

Findings

Analytical integral expressions for photon spectra in nonlinear Compton scattering.

Elucidation of crossing symmetry between pair production and Compton scattering.

Extension of previous models to non-counterpropagating photon configurations.

Abstract

In [Phys. Rev. Lett. \textbf{117}, 213201 (2016)] we have determined the angular resolved and the total energy spectrum of a positron produced via nonlinear Breit-Wheeler pair production by a high-energy photon counterpropagating with respect to a tightly focused laser beam. Here, we first generalize the results in [Phys. Rev. Lett. \textbf{117}, 213201 (2016)] by including the possibility that the incoming photon is not exactly counterpropagating with respect to the laser field. As main focus of the present paper, we determine the photon angular resolved and total energy spectrum for the related process of nonlinear Compton scattering by an electron impinging into a tightly-focused laser beam. Analytical integral expressions are obtained under the realistic assumption that the energy of the incoming electron is the largest dynamical energy of the problem and that the electron is initially almost counterpropagating with respect to the laser field. The crossing symmetry relation between the two processes in a tightly focused laser beam is also elucidated.