# Resonant photoproduction of high-energy electron-positron pairs in the field of a nucleus and a plane electromagnetic wave

## TL;DR

This paper theoretically investigates the resonant photoproduction of ultrarelativistic electron-positron pairs in a nuclear and laser field, revealing conditions for resonance and potential for significantly enhanced cross sections in high-energy photon interactions.

## Contribution

It introduces a detailed theoretical analysis of resonant conditions in electron-positron pair production involving a nuclear and laser field, showing how resonance enhances the process.

## Key findings

- Resonance occurs only for initial photon energies above a threshold.
- Resonant pairs propagate in a narrow cone along initial photon direction.
- Resonant cross section can greatly exceed non-resonant values.

## Abstract

The resonant photoproduction of ultrarelativistic electron-positron pairs (PPP) in a nuclear field and a weak laser field is theoretically studied. Under resonance conditions, the intermediate virtual electron (positron) in the laser field becomes a real particle. As a result, the initial process of the second order in the fine structure constant in the laser field effectively reduces into two successive processes of the first order: single-photon production of electron-positron pair in a laser field (laser-stimulated Breit-Wheeler process) and laser-assisted process of electron (positron) scattering on a nucleus. Resonant kinematics of PPP is studied in details. It is shown that for the considered laser intensities resonance is possible only for the initial photon energies greater than the characteristic threshold energy. At the same time, the ultrarelativistic electron and positron propagate in a narrow cone along the direction of the initial photon momentum. The resonant energy of the positron (electron) can has two values for each radiation angle which varies from zero to some maximum value determined by the energy of the initial photon and the threshold energy. Resonant differential cross section of the studied process was obtained. It is shown that the resonant differential cross section of the PPP can significantly exceed the corresponding cross section of the PPP without an external field. The project calculations may be experimentally verified by the scientific facilities of pulsed laser radiation (SLAC, FAIR, XFEL, ELI, XCELS)