Precise Measurement of the Left-Right Cross Section Asymmetry in $Z$ Boson Production by $\ee$ Collisions

TL;DR

This paper reports a precise measurement of the left-right asymmetry in Z boson production from electron-positron collisions, providing a key determination of the weak mixing angle with high accuracy.

Contribution

The study presents the most precise measurement of the $A_{LR}$ asymmetry at the Z pole, improving the accuracy of the weak mixing angle determination.

Findings

Measured $A_{LR}$ to be 0.1628±0.0071(stat.)±0.0028(syst.)

Determined the effective weak mixing angle to be 0.2292±0.0009(stat.)±0.0004(syst.)

Achieved high precision in asymmetry measurement at 91.26 GeV

Abstract

We present a precise measurement of the left-right cross section asymmetry ($A_{LR}$) for $Z$ boson production by $\ee$ collisions. The measurement was performed at a center-of-mass energy of 91.26 GeV with the SLD detector at the SLAC Linear Collider (SLC). The luminosity-weighted average polarization of the SLC electron beam was (63.0$\pm$1.1)%. Using a sample of 49,392 $\z0$ decays, we measure $A_{LR}$ to be 0.1628$\pm$0.0071(stat.)$\pm$0.0028(syst.) which determines the effective weak mixing angle to be $\swein=0.2292\pm0.0009({\rm stat.})\pm0.0004({\rm syst.})$.}