Measurement of the tau lifetime

Abstract

We have used a high-resolution drift chamber in the Mark II detector at the SLAC storage ring PEP to measure the lifetime of \ensuremath{\tau} leptons produced in ${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$ annihilations at 29 GeV. Based on the flight-path distribution of 807 three-prong \ensuremath{\tau} decays, the lifetime is found to be (2.88\ifmmode\pm\else\textpm\fi{}0.16 \ifmmode\pm\else\textpm\fi{}0.17)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}13}$ sec, in agreement with expectations for e-\ensuremath{\mu}-\ensuremath{\tau} universality.