Observation of the decay τ → ϱππντ

Abstract An analysis of the decay τ − → π − π − π + π 0 ν τ has been performed with the ARGUS detector at the DORISII storage ring. From a study of the two pion subsystems we have found first evidence for the decays τ − → ϱ 0 π − π 0 ν τ , τ − → ϱ − π + π − ν τ , and τ − → ϱ + π − π − ν τ with relative contributions to the decay τ − → π − π − π + π 0 ν τ of 0.30 ± 0.04, 0.26 ± 0.05, and 0.10 ± 0.03, respectively. The fraction of the subchannel τ − → ωπ − ν τ has been determined to be 0.33 ± 0.05. The production of ϱ mesons is enhanced by a factor of 1.9 ± 0.3 over that of ω mesons. We conclude that in more than 81% (95% CL) of all τ − → π − π − π + π 0 ν τ decays either a ϱ or ω meson is produced.