Extended locally monochromatic approximations of strong-field QED processes
Year: 2025
Type: article
Abstract: Strong-field QED (SFQED) probability rates in the locally monochromatic approximation (LMA) have become an indispensable tool for simulations of processes like gamma-ray emission or electron-positron pair production in laser-particle collisions. We revisit the LMA derivation and explicitly demonstrate that it is based on the separation of timescales, neglect of the long-range interference effects, and subsequent averaging over the cycle scale. Doing so, we obtain unambiguously LMA rates for arbitrary polarizations of the plane-wave background. Additionally, we partially restore the finite bandwidth effects that are lost in the LMA derivation. We refer to the bandwidth-restored result as the LMA + and show that it agrees with the full SFQED predictions better than the standard LMA. We use LMA + to address previously inaccessible observables and formulate an additional limitation on the applicability of locally monochromatic approximations in general. We provide analytical results for the angular-integrated LMA + probability rate and the fully differential probability that account for the finite bandwidth effects.
Source: Physical Review A
DOI: 10.1103/cmmp-rt2g
Authors: Nikita Larin, Daniel Seipt
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $2,675
OpenAlex ID: W4414593310