Precision electroweak tests of the Standard Model

Abstract

The present status of precision electroweak data is reviewed.These data include measurements of e+e-→f\\barf, taken at the Z resonance at LEP, which are used to determine the mass and width of the Z-boson. In addition, measurementshave also been made of the forward-backward asymmetries for leptonsand heavy-quarks, and also the final state polarization of theτ-lepton. At SLAC, where the electron beam was polarized,measurements were made of the left-right polarized asymmetry, ALR, and the left-right forward-backward asymmetries for b- and c-quarks.The mass, mW, and width, ΓW, of the W-boson have been measuredat the Tevatron and at LEP, and the mass of the top-quark, mt, has beenmeasured at the Tevatron. These data, plus other electroweak data, areused in global electroweak fits in which various Standard Model (SM) parameters are determined.A comparison is made between the results of the direct measurementsof mW and mt with the indirect results coming from electroweak radiative corrections. Using all precision electroweak data, fits are also made to determine limits onthe mass of the Higgs boson, mH. The influence on these limits of specificmeasurements, particularly those which are somewhat inconsistent with theSM, is explored. The data are also analysed in terms of the quasi-model-independent ϵ variables.Finally, the impact on the electroweak fits of the improvements in the determination of the W-boson and top-quark masses, expected from the Tevatron Run 2, is examined.