Measurement of electroweak parameters from Z decays into fermion pairs

We report on the properties of the Z resonance from 62500 Z decays into fermion pairs collected with the ALEPH detector at LEP, the Large Electron-Positron storage ring at CERN. We find MZ=(91.193±0.016exp±0.030LEP) GeV, ΓZ=(2497±31) MeV, σhad0=(41.86±0.66) nb, and for the partial widths Γinv=(489±24) MeV, Γhad=(1754±27) MeV, Γee=(85.0±1.6) MeV, Γμμ=(80.0±2.5) MeV, and Γττ=(81.3±2.5) MeV, all in good agreement with the Standard Model. Assuming lepton universality and using a lepton sample without distinction of the final state we measure Γll=(84.3±1.3) MeV. The forward-backward asymmetry in leptonic decays is used to determine the vector and axial-vector weak coupling constants of leptons, gV2(MZ2)=(0.12±0.12)x10-2 and gA2(MZ2)=0.2528±0.0040. The number of light neutrino species is Nν=2.91±0.13; the electroweak mixing angle is sin2θW(MZ2)=0.2291±0.0040. (orig.)