BUSKULIC, D (reprint author), LAB PHYS PARTICLES,CNRS,IN2P3,F-74019 ANNEDY VIEUX,FRANCE.
Based on 520000 fermion pairs accumulated during the first three years of data collection by the ALEPH detector at LEP, updated values of the resonance parameters of the Z are determined to be M(Z) = (91.187 +/- 0.009) GeV, GAMMA(Z) = (2.501 +/- 0.012) GeV, sigma(had)0 = (41.60 +/- 0.27) nb, and R(l) = 20.78 +/- 0.13. The corresponding number of light neutrino species is N(v) = 2.97 +/- 0.05. The forward-backward asymmetry in lepton-pair decays is used to determine the ratio of vector to axial-vector couplings of leptons: g(V)2(M(z)2)/g(A)2 (M(Z)2) = 0.0052 +/- 0.00 1 6. Combining this with ALEPH measurements of the b and c quark asymmetries and tau polarization gives sin2theta(W)eff = 0.2326 +/- 0.0013. Assuming the minimal Standard Model, and including measurements of M(W)/M(Z) from ppBAR colliders and neutrino-nucleon scattering, the mass of the top quark is M(top)=156 +/-22/25 +/-17/22 Higgs GeV.