# Resonant high-energy bremsstrahlung of ultrarelativistic electrons in the field of a nucleus and an electromagnetic wave

## TL;DR

This paper explores the resonant bremsstrahlung process of ultrarelativistic electrons in a nuclear and electromagnetic field, revealing two distinct reaction channels with enhanced cross-sections that can be experimentally validated.

## Contribution

It introduces a detailed theoretical analysis of resonant spontaneous bremsstrahlung, identifying two reaction channels and their distinct resonant behaviors, expanding understanding of electron-nucleus interactions in laser fields.

## Key findings

- Resonance can develop in two separate reaction channels.
- The cross-section in resonance significantly exceeds non-resonant cases.
- Distinct angular and frequency dependencies characterize each reaction channel.

## Abstract

The actual theoretical research investigates the resonant spontaneous bremsstrahlung (RSB) of ultrarelativistic electrons under the condition of scattering on a nucleus in the field of a weak electromagnetic wave. The progression of the functional mechanism indicates the transformation of the intermediate virtual electron into the real particle state. As a result, the initial second order process with accordance to the fine structure constant in the light field productively splits into two consequent first order formations: the laser-stimulated Compton effect and the laser-assisted scattering of an electron on a nucleus. It is important to emphasize that the resonance escalation possesses a possibility to develop within two reaction channels. Therefore, the first channel - delineates the occurrence that correlates to the spontaneous photon emission by an electron with subsequent scattering on a nucleus. The second channel - illustrates the configuration corresponding to the electron scattering on a nucleus with consecutive spontaneous photon emission in the wave field. Moreover, the spontaneous photon radiation angle allocates a single-valued dependency with the resonant frequency for the first channel in contrast to the second displacement that categorizes a composite area with three various resonant frequency magnitudes for the particular emission angle diapason. The project data analysis proposes that the reaction channels do not interfere within the whole range of observation. To summarize, the investigation calculates that the particular cross-section within the resonant ambience significantly exceeds the according cross-section in the approximation of an external field absence. In conclusion, numerous scientific facilities with specialization in pulsed laser radiation (SLAC, FAIR, XFEL, ELI, XCELS) may experimentally validate the computational estimations.