Delbr\"uck scattering in combined Coulomb and laser fields

TL;DR

This paper investigates Delbrück scattering in combined Coulomb and laser fields, revealing significant differences in angular distribution and cross section enhancements due to laser parameters, with implications for experimental observation.

Contribution

It provides an exact calculation of Delbrück scattering amplitudes in laser fields of arbitrary strength and polarization, extending previous models limited to simpler conditions.

Findings

Angular distribution differs markedly from pure Coulomb case.

Cross section can be significantly increased with realistic laser parameters.

High order effects in laser intensity parameter are crucial even at small values.

Abstract

We study Delbr\"uck scattering in a Coulomb field in the presence of a laser field. The amplitudes are calculated in the Born approximation with respect to the Coulomb field and exactly in the parameters of the laser field having arbitrary strength, spectral content and polarization. The case of high energy initial photon energy is investigated in detail for a monochromatic circularly polarized laser field. It is shown that the angular distribution of the process substantially differs from that for Delbr\"uck scattering in a pure Coulomb field. The value of the cross section under discussion may exceed the latter at realistic laser parameters that essentially simplify the possibility of the experimental observation of the phenomenon. The effect of high order terms in the quantum intensity parameter $\chi$ of the laser field is found to be very important already at relatively small $\chi$.