τ LEPTON PHYSICS

Abstract

General properties of the τ leptons are reviewed using the recent measurements of production and decay of τ leptons. The improvements in the knowledge of the τ mass and the limits on ντ mass are reported. New improved measurements of the τ polarization and asymmetries performed at LEP and SLC prove a measurement of the axial and vector part of the neutral current at the per mil level. For the leptonic charged current, no deviation from the V–A Lorentz structure of the current is observed. Improvements on the lifetime and leptonic branching fractions allow a check of the charged current universality at the 0.5% level. New hadronic decay channels have been measured, mainly those involving kaons and η mesons. A precise determination of αs at the τ mass energy scale is performed. Finally, tests of possible new physics beyond the Standard Model are discussed.