First Direct Measurement of the Parity-Violating Coupling of the Z^0 to the s-Quark

TL;DR

This paper reports the first direct measurement of the parity-violating coupling of the Z^0 boson to strange quarks, using polarized electron collisions and strange hadron tagging to determine the coupling value.

Contribution

It provides the first direct experimental determination of the Z^0 to strange quark parity-violating coupling, improving understanding of electroweak interactions.

Findings

Measured A_s = 0.895 ± 0.066 (stat) ± 0.062 (syst)

Used polarized electron beam and strange hadron tagging techniques

Constrained analyzing power and background using data

Abstract

We have made the first direct measurement of the parity-violating coupling of the Z^0 boson to the strange quark, A_s, using ~550,000 e^+e^- ->Z^0->hadrons events produced with a polarized electron beam and recorded by the SLD experiment. Z^0 -> s-sbar events were tagged by the absence of B or D hadrons and the presence in each hemisphere of a high-momentum K^+- or K^0_s. From the polar angle distributions of the strangeness-signed thrust axis, we obtained A_s=0.895+-0.066(stat.)+-0.062(syst.). The analyzing power and u-ubar plus d-dbar background were constrained using the data.