Worldline description of scattering processes in ultra intense lasers: plane waves and beyond

The strong field and non-perturbative regime necessitated by the modeling of quantum field theory in the presence of an ultra-intense laser background requires new techniques beyond the diagrammatic approach well describing quantum electrodynamics (QED). I discuss an application of the worldline formalism, in which second-quantized fields are studied using an inherently non-perturbative first-quantized representation, to exactly model electron-photon scattering processes in plane waves and non-null backgrounds with arbitrary intensity. For realistic modeling of lasers with an optical carrier frequency, non-null fields result from interactions with a background plasma being treated as a refractive index.

I present formulae for an arbitrary number of N-photon tree-level scattering processes for plane waves [1] and non-null “shockwave” fields [2]; by virtue of the worldline formalism these take on a compact form and are exact to all orders in the background field. A low-energy limit of the N-photons in a constant crossed field is also considered, wherein I show a remarkably simple form arises. Ongoing studies on higher-loop corrections will briefly be discussed.