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 {ital A}{sub {ital b}} and {ital A}{sub {ital c}} are directly measured by the SLD experiment at the SLAC Linear Collider in {ital e}{sup +}{ital e}{sup {minus}} collisions with polarized electrons at the {ital Z}{sup 0} resonance. Leptons with distinctive total and transverse momenta are used to select and analyze {ital Z}{sup 0}{r_arrow}{ital bc}{ovr bar} events. {ital A}{sub {ital b}} and {ital A}{sub {ital c}} 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{sup --1} of {ital Z}{sup 0} decay data with an average electron beam polarization of 63% we find {ital A}{sub {ital b}}=0.91{plus_minus}0.14 (stat) {plus_minus}0.07 (syst) and {ital A}{sub {ital c}}=0.37{plus_minus}0.23 (stat) {plus_minus}0.21 (syst).