Measurement of the tau lifetime with the DELPHI detector

The tau lepton lifetime has been measured with the e+e−→τ+τ− events collected by the DELPHI detector at LEP in the years 1991-1995. Three different methods have been exploited, using both one-prong and three-prong τ decay channels. These are combined with previously published DELPHI results to provide a tau lifetime measurement of ττ=290.9±1.4stat±1.0sys fs, using the full LEP1 data sample.