Measurement of the weak mixing angle at a Super Charm-Tau factory with data-driven monitoring of the average electron beam polarization

TL;DR

This paper proposes a data-driven method to measure the average electron beam polarization at a Super Charm-Tau factory, enabling precise weak mixing angle measurements through analysis of specific decay processes.

Contribution

A novel approach utilizing the differential cross-section of a specific decay channel to determine electron beam polarization with high statistical precision.

Findings

Achieves polarization measurement precision better than 10^{-3}

Applicable at high luminosity of 10^{35} cm^{-2}s^{-1}

Supports accurate weak mixing angle determination

Abstract

A method for measuring the average longitudinal polarization of the electron beam at an electron-positron collider operating near the $J/\psi$ resonance is proposed. The method utilizes the differential cross-section of $J/\psi\to [\Lambda\to p\pi^-][\bar{\Lambda}\to\bar{p}\pi^+]$ decay. It can be used to measure the average longitudinal polarization of electrons with the statistical precision better than $10^{-3}$ at a Super Charm-Tau factory operating at the luminosity of $10^{35}~\mathrm{cm}{}^{-2}\mathrm{s}{}^{-1}$. The method is discussed in the context of the weak mixing angle measurement in the same experiment.