This paper reports a new measurement of the branching ratio for the decay ${\tau }^{-}\to e^{-}{\overline{\nu }}_e{\nu }_{\tau }$. The data were taken with the High Resolution Spectrometer at the SLAC $e^{+}{e}^{-}$ colliding-beam facility PEP, operating at $\sqrt{s}=29\mathrm{}$ GeV. The result $B({\tau }^{-}\to e^{-}{\overline{\nu }}_e{\nu }_{\tau })=(17.0\mathrm{}\pm 0.5\pm 0.6)\%$, together with our measurements of the lifetime and the topological branching fractions of the $\tau$ lepton are compared with theoretical expectations.

• Received 1 August 1989

DOI:https://doi.org/10.1103/PhysRevD.41.1414