A Combination of Preliminary Electroweak Measurements and Constraints on the Standard Model, 1999

This note presents a combination of published and preliminary electroweak results from the four LEP collaborations and the SLD collaboration which were prepared for the 1998 summer conferences. Averages are derived for hadronic and leptonic cross-sections, the leptonic forward-backward asymmetries, the *polarisation asymmetries, the bb and cc partial widths and forward-backward asymmetries and the qq charge asymmetry. The major changes with respect to results presented in summer 1997 are updates to the measurements of the Z lineshape, tau polarisation, W mass and triple-gaugeboson couplings from LEP, and ALR from SLD. The results are compared with precise electroweak measurements from other experiments. A signifi- cant update here is a new measurement of the mixing angle from the NuTeV Collaboration. The parameters of the Standard Model are evaluated, first using the combined LEP electroweak measurements, and then using the full set of electroweak results.