Measurement of the Parity-Violation Parameters Ab and Ac from the Left-Right Forward-Backward Asymmetry of Leptons in Hadronic Events at the Z0 Resonance

The parity-violating parameters Ab and Ac are directly measured by the SLD experiment at the SLAC Linear Collider in e+e- collisions with polarized electrons at the Z0 resonance. Leptons with distinctive total and transverse momenta are used to select and analyze Z0→bb¯ and Z0→cc¯ events. Ab and Ac are extracted by forming the left-right forward-backward asymmetry in electron beam polarization and quark polar angle. From our 1993 sample of 1.8 pb–1 of Z0 decay data with an average electron beam polarization of 63% we find Ab=0.91±0.14 (stat) ± 0.07 (syst) and Ac=0.37±0.23 (stat) ± 0.21 (syst).