An Improved Direct Measurement of Leptonic Coupling Asymmetries with Polarized Z0’s

We report new direct measurements of the Z-lepton coupling asymmetry parameters Ae, A and A , with polarized Z '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 Ae = 0:1558 0:0064, A = 0:137 0:016 andA = 0:142 0:016. If lepton universality is assumed, a combined asymmetry parameter Al = 0:1523 0:0057 results. This translates into an e ective weak mixing angle sin eff W = 0:23085 0:00073 at the Z 0 resonance. Paper Contributed to the XIXth International Symposium on Lepton Photon Interactions, August 9-14 1999, Stanford, USA. Work supported in part by the Department of Energy contract DE{AC03{76SF00515.