A study of the decay tau- → π-νsub(tau)

We present a high statistics measurement of the branching ratio for the decay tau- → π-νsub(tau) using data obtained with the Mark II detector at the SLAC e+e- storage ring SPEAR. We have used events from the center-of-mass energy region 3.52 to 6.7 GeV to determine that B(tau- → π-νsub(tau)) = 0.117 +- 0.004 +- 0.018. From electron-muon events in the same data sample, we have determined that B (tau- → π-anti νsub(tau))/B(tau- → e-νsub(e)νsub(tau)) = 0.66 +- 0.03 +- 0.11. We present measurements of the mass and spin of the tau and the mass of the tau neutrino based, for the first time, on a hadronic decay mode of the tau. (orig.)