Strong field effects in laser pulses: the Wigner formalism

TL;DR

This paper uses the Wigner formalism to analyze strong field quantum electrodynamics effects in laser pulses, revealing effective mass shifts, multi-photon processes, and vacuum pair production in intense laser backgrounds.

Contribution

It provides an exact phase space calculation of the Wigner function in strong null-field backgrounds using lightfront field theory, extending understanding of strong field QED phenomena.

Findings

Identification of effective mass in laser pulses

Comparison with mass shift in plane waves

Signals of multi-photon absorption and emission

Abstract

We investigate strong field vacuum effects using a phase space approach based on the Wigner formalism. We calculate the Wigner function in a strong null-field background exactly, using lightfront field theory. The Wigner function exhibits the distinct features of strong field QED: in particular we identify the effective mass in a laser pulse, compare it to the well-known mass shift in a periodic plane wave and identify signals of multi-photon absorption and emission. Finally, we show how to extend our results to describe vacuum pair production in colliding laser pulses.