An Improved Measurement of the Left-Right Z0 Cross Section Asymmetry

TL;DR

This paper reports a precise measurement of the left-right asymmetry in Z boson production at the SLAC collider, providing insights into electroweak interactions and the weak mixing angle.

Contribution

It introduces an improved measurement technique for ALR at the Z pole, achieving higher precision than previous experiments.

Findings

Measured ALR0 as 0.1512±0.0042 (stat.)±0.0011 (syst.)

Determined the effective weak mixing angle as 0.23100±0.00054 (stat.)±0.00014 (syst.)

Enhanced the precision of electroweak parameter measurements

Abstract

We present a new measurement of the left-right cross section asymmetry (ALR) for Z boson production by e+e- collisions. The measurement was performed at a center-of-mass energy of 91.28 GeV with the SLD detector at the SLAC Linear Collider (SLC). The luminosity-weighted average polarization of the SLC electron beam was (77.23+-0.52)%. Using a sample of 93,644 Z decays, we measure the pole-value of the asymmetry, ALR0, to be 0.1512+-0.0042(stat.)+-0.0011(syst.) which is equivalent to an effective weak mixing angle of sin**2(theta_eff)=0.23100+-0.00054(stat.)+-0.00014(syst.).