Analysis of Z0 couplings to charged leptons

The couplings of the Z0 to charged leptons are studied using measurements of the lepton pair cross sections and forward-backward asymmetries at centre of mass energies near to the mass of the Z0. The data are consistent with lepton universality. Using a parametrisation of the lepton pair differential cross section which assumes that the Z0 has only vector and axial couplings to leptons, the charged leptonic partial decay width of the Z0 is determined to be Гol+ol− = 83.1±1.9 MeV and the square of the product of the effective axial vector and vector coupling constants of the Z0 to charged leptons to be ǎ2olv̌2ol = 0.0039± 0.0083, in agreement with the standard model. A parametrisation in the form of the improved Born approximation gives effective leptonic axial vector and vector coupling constants ǎ2ol = 0.998±0.024 and v̌2ol = 0.0044±0.0083. In the framework of the standard model, the values of the parameters ϱz and sin2θw are found to be 0.998±0.024 and 0.233+0.045−0.012 respectively. Using the relationship in the minimal standard model between ϱz and sin2θw, the results sin2θSMw = 0.233+0.007−0.006 is obtained. Our previously published measurement of the ratio of the hadronic to the leptonic partial width of the Z0 is update: Rz = 21.72+0.71−0.65.