An upper limit for the tau-neutrino mass from tau -> 5 pi(+/-)nu(tau) decays

An upper limit for the tau-neutrino mass has been determined from the decay tau --> 5 pi(+/-)nu(tau) using data collected with the OPAL detector from 1991 to 1995 in e(+)e(-) collisions at root s approximate to M-Z. A limit of 43.2 MeV at 95% CL is obtained using a two-dimensional method in the 5 pi invariant mass and energy distribution from 22 selected events. Combining this result with OPAL's previously published measurement using tau(+)tau(-) --> 3h+/- (tau) + 3h(-/+)nu(tau) decays, a new combined limit of m(nu tau) < 27.6 MeV (95% CL) is obtained.