# Spin-polarization effects of an ultrarelativistic electron beam in an ultraintense two-color laser pulse

## TL;DR

This paper investigates how ultrarelativistic electron beams become spin-polarized when colliding with ultraintense two-color laser pulses, revealing asymmetries and polarization effects driven by quantum radiation processes.

## Contribution

It introduces a Monte Carlo simulation approach to analyze spin-resolved electron dynamics in two-color laser fields, highlighting the impact of field asymmetry and phase on polarization.

## Key findings

- Electron radiation probabilities are asymmetric in the two-color field.
- Electron beams can achieve about 11% total polarization.
- Partial polarization can reach up to 63% depending on phase.

## Abstract

Spin-polarization effects of an ultrarelativistic electron beam head-on colliding with an ultraintense two-color laser pulse are investigated comprehensively in the quantum radiation-dominated regime. We employ a Monte Carlo method, derived from the recent work of [Phys. Rev. Lett. {\bf 122}, 154801 (2019)], to calculate the spin-resolved electron dynamics and photon emissions in the local constant field approximation. We find that electron radiation probabilities in adjacent half cycles of a two-color laser field are substantially asymmetric due to the asymmetric field strengths, and consequently, after interaction the electron beam can obtain a total polarization of about 11\% and a partial polarization of up to about 63\% because of radiative spin effects, with currently achievable laser facilities, which may be utilized in high-energy physics and nuclear physics. Moreover, the considered effects are shown to be crucially determined by the relative phase of the two-color laser field and robust with respect to other laser and electron beam parameters.