Loops and polarization in strong-field QED

Understand

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.