Using data from the CLEO II detector at CESR, we measure the τ-lepton mass by exploiting the unique kinematics of events in which both τ's decay hadronically. The result is mτ=1777.8±0.7±1.7 MeV/c2. By comparing our result with other measurements near τ-pair threshold, we extract an upper limit on the τ-neutrino mass of 75 MeV/c2 at 95% confidence level.
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics