Measurement of theτ-Lepton Lifetime

Abstract

We report a new and precise measurement of the lifetime of the $\tau$ lepton. The data were taken with the High Resolution Spectrometer at the SLAC $e^{+}{e}^{-}$ colliding-beam facility PEP operating at 29 GeV center-of-mass energy. The flight distances of 1311 $\tau$ decays to three charged particles were measured with a four-layer tubular-cell vertex chamber in conjunction with the main drift chamber. The resulting lifetime of the $\tau$ lepton is ${\tau }_{\tau }=(2.99\mathrm{}\pm 0.15\pm 0.10)\times {10}^{-13\mathrm{}}$ sec.