Parity Violation on Longitudinal Single-Spin Asymmetries at the EicC

TL;DR

This paper investigates parity-violating asymmetries in deep inelastic scattering at the EicC, finding that these asymmetries can be used to precisely measure the weak mixing angle, with potential for high accuracy.

Contribution

It introduces the first detailed estimates of parity-violating asymmetries at EicC and proposes using these measurements to extract the weak mixing angle with high precision.

Findings

$A_{PV}^e$ is 10^{-4} and larger than $A_{PV}^p$ by 1-3 orders of magnitude.

Uncertainty analysis identifies dominant sources across different Bjorken-$x$ regimes.

A relative precision below 10% for the weak mixing angle measurement is achievable within one year.

Abstract

We explore two longitudinal single-spin asymmetries induced from parity violation in neutral-current deep inelastic scattering at the proposed Electron-ion collider in China (EicC): $A_{PV}^{e\,(p)}$ from longitudinally polarized (unpolarized) electrons scattering off unpolarized (longitudinally polarized) protons. We find $A_{PV}^e$, of $\mathcal{O}(10^{-4})$, is generically one to three orders of magnitude larger than $A_{PV}^p$. We further estimate different uncertainty sources including statistics, parton distribution functions, and beam polarization, for both asymmetries, and then identify individually their dominance in different regimes of the Bjorken-$x$. Based on these results, we then advocate utilizing $A_{PV}^p$ for the extraction of the weak mixing angle at two representative momentum transfer scales unexplored before, and we find a relative precision below 10% can be achieved at the EicC with an effective one-year operation time.