Resonant photoproduction of ultrarelativistic electron-positron pairs on a nucleus in strong monochromatic light field

TL;DR

This paper analytically investigates resonant laser-assisted electron-positron pair photoproduction on a nucleus in a strong monochromatic light field, revealing conditions for resonance and enhanced cross sections that can test quantum electrodynamics in strong fields.

Contribution

It provides an analytical description of the resonant process, detailing the kinematics, resonance conditions, and the significant increase in cross section due to the external field, advancing understanding of QED in strong backgrounds.

Findings

Resonant energies depend ambiguously on outgoing particle angles.

A minimal number of absorbed photons is necessary for resonance.

Resonant cross section exceeds non-field case in specific kinematic regions.

Abstract

For complete development of quantum electrodynamics in the presence of a strong external field, the proper understanding of resonant processes and all their peculiarities is essential. We present our attempt to analytically investigate the resonant case of laser-assisted electron-positron pair photoproduction on a nucleus. Due to the presence of external field, the intermediate virtual particle may become real, herewith the second order process in the fine structure constant effectively reduces into the two successive first order processes. All inherent kinematics features were discussed in details and the resonant differential cross section was obtained. We established that the resonant energies of produced particles ambiguously depend on the positron (channel A) or electron (channel B) outgoing angle, and the certain minimal amount of absorbed wave photons are required for resonance to happen. Furthermore, the resonant cross section significantly exceeds the corresponding one in the absence of the external field within the particular kinematic regions and consequently, the considered process can be used qua a marker for probing theoretical predictions of quantum electrodynamics with strong background field.