Measurement of the decay τ-→π-π+π-2π0ντ

The decay τ - →π - p + p - 2π 0 n τ , has been observed in e + e - annihilation using the CLEO II detect at the Cornell Electron Storage Ring. In a data sample collected at √-s∼10.6 GeV, 668±38 decay candidates have been identified by exclusively reconstructing two π 0, s, accompanying three charged particles, which are assumed to be pions. Normalizing to the number of τ pairs detected with one charged particle recoiling against three charged particles, this yields a branching ratio of B 3π2π0 =(0.48±0.04±0.04)%