Investigation of beam self-polarization in the future $e^{+}e^{-}$ circular collider

TL;DR

This paper explores the potential for beam self-polarization in the future FCC-$e^{+}e^{-}$ collider, analyzing simulation results to assess the feasibility of using self-polarized leptons for precise energy measurements.

Contribution

It presents the first simulation-based investigation into beam self-polarization in the FCC-$e^{+}e^{-}$, considering realistic errors and misalignments.

Findings

Preliminary simulations show potential for self-polarization under certain conditions.

Quadrupole misalignments and BPM errors impact polarization levels.

Self-polarization could enhance energy measurement precision.

Abstract

The use of resonant depolarization has been suggested for precise beam energy measurements (better than 100 keV) in the $e^{+}e^{-}$ Future Circular Collider (FCC-$e^{+}e^{-}$) for Z and WW physics at 45 and 80 GeV beam energy respectively. Longitudinal beam polarization would benefit the Z peak physics program; however it is not essential and therefore it will be not investigated here. In this paper the possibility of self-polarized leptons is considered. Preliminary results of simulations in presence of quadrupole misalignments and beam position monitors (BPMs) errors for a simplified FCC-$e^{+}e^{-}$ ring are presented.