Effect of a strong laser field on $e^+ e^-$ photoproduction by relativistic nuclei

TL;DR

This paper investigates how a strong laser field influences electron-positron photoproduction by relativistic nuclei, revealing significant suppression or enhancement of production rates depending on photon energy and polarization, with effects measurable by current technology.

Contribution

The study provides an exact analysis of laser field effects on Bethe-Heitler photoproduction, highlighting polarization dependence and conditions for observable rate modifications.

Findings

Laser field can suppress or enhance pair production rates.

Polarization alignment affects the efficiency of the process.

Effects are measurable with current proton accelerators and laser systems.

Abstract

We study the influence of a strong laser field on the Bethe-Heitler photoproduction process by a relativistic nucleus. The laser field propagates in the same direction as the incoming high-energy photon and it is taken into account exactly in the calculations. Two cases are considered in detail. In the first case, the energy of the incoming photon in the nucleus rest frame is much larger than the electron's rest energy. The presence of the laser field may significantly suppress the photoproduction rate at soon available values of laser parameters. In the second case, the energy of the incoming photon in the rest frame of the nucleus is less than and close to the electron-positron pair production threshold. The presence of the laser field allows for the pair production process and the obtained electron-positron rate is much larger than in the presence of only the laser and the nuclear field. In both cases we have observed a strong dependence of the rate on the mutual polarization of the laser field and of the high-energy photon and the most favorable configuration is with laser field and high-energy photon linearly polarized in the same direction. The effects discussed are in principle measurable with presently available proton accelerators and laser systems.