An Improved Direct Measurement of Leptonic Coupling Asymmetries with Polarized Z{sup 0}'s

Abstract

We report new direct measurements of the Z{sup 0}-lepton coupling asymmetry parameters A{sub e}, A{sub {mu}} and A{sub r}, with polarized Z{sup 0}'s collected by the SLD detector at the SLAC Linear Collider. The parameters are extracted from the measurement of the left-right-forward-backward asymmetries for each lepton species. The 1996, 1997 and 1998 SLD runs are included in this analysis and combined with published data from the 1993-95 runs. Preliminary results are A{sub e} = 0.1558 {+-} 0.0064, A{sub {mu}} = 0.137 {+-} 0.016 and A{sub {tau}} = 0.142 {+-} 0.016. If lepton universality is assumed, a combined asymmetry parameter A{sub l} = 0.1523 {+-} 0.0057 results. This translates into an effective weak mixing angle sin{sup 2} {theta}{sub W}{sup eff} = 0.23085 {+-} 0.00073 at the Z{sup 0} resonance.