Recent Results from the SLD Using a Highly Polarized Electron Beam

New results are presented on the fermion asymmetries, Ab and A,, and the b-branching ratio, &, using a data sample of 150,OOOZ” decays collected by the SLD during 1993 and 1994. The fermion asymmetries exploit the highly polarized electron beam available at the SLC (63.0% f 1.1% during 1993 and increasing to a preliminary value of 78.2% f 2.0% during 1994) to perform direct measurements of Ab and A,. The preliminary results obtained are Ab = 0.82 f O.OG(stat)+O.O8(syst), A, = 0.63 f 0.13(stat)fO.O8(syst) and Rb = 0.218 2 0.004(stat)*O.O04(syst) fO.O03(R,). In addition, the measurement of sin2 e$’ from the 1993 ALR result is reviewed. The result obtained is sin2 8gf = 0.2292 f 0.0009(stat)f0.0004(syst). ‘This work was supported by Department of Energy contracts: DE-FG02-91ER40676 (BU), DE-FG0392ER40701 (CIT), DE-FG03-91ER40618 (UCSB), DE-FG03-92ER40689 (UCSC), DE-FG03-93ER40788 (CSU), DE-FG02-91ER40672 (C o orado), 1 DE-FG02-91ER40677 (Ill inois), DE-AC03-76SF00098 (LBL), DE-FG02-92ER40715 (Massachusetts), DE-AC02-76ER03069 (MIT), DE-FGOB-85ER40224 (Oregon), DE-AC03-76SF00515 (SLAC), DE-FG05-91ER40627 (Tennessee), DE-AC02-76ER00881 (Wisconsin), DE-FG02-92ER40704 (Yale); National Science Foundation grants: PHY-91-13428 (UCSC), PHY-8921320 (Columbia), PHY-92-04239 (C incinnati), PHY-88-17930 (Rutgers), PHY-88-19316 (Vanderbilt), PHY-92-03212 (Washington); the UK Science and Engineering Research Council (Brunel and RAL); the Istituto Nazionale di Fisica Nucleare of Italy (Bologna, Ferrara, Frascati, Pisa, Padova, Perugia); and the Japan-US Cooperative Research Project on High Energy Physics (Nagoya, Tohoku).