During 1993 and 1995 LEP was run at 3 energies near the Z peak in order to give improved measurements of the mass and width of the resonance. During 1994, LEP operated only at the Z peak. In total DELPHI accumulated data corresponding to an integrated luminosity of approximately 116 pb. Analyses of the hadronic cross-sections and of the cross-sections and forward-backward asymmetries in the leptonic channels used the most precise evaluations of the LEP energies. In the dimuon channel, events with a photon radiated from the initial state have been used to probe the cross-sections and asymmetries down to PETRA energies. Model independent fits to all DELPHI lineshape and asymmetry data from 1990 to 1995 have been carried out giving values of the resonance parameters: These values are significantly more precise than those previously published. The results are interpreted in terms of the Sta... [Llegir més ...]