| Popis: |
21 pp. (1978).
Decays of the heavy lepton τ have now been observed in e+e− ‐ collisions at the energy of the ψ′‐resonace, which results in an improved mass determination Mτ=1.807±0.020 GeV. For the τ‐life‐time a new upper limit of ττ?3.5⋅10−12 sec. is given. The evidence for the decay τ→νπρ has been strengthened, and the πρ‐system is found to be in an S‐wave state with JP=1+, proving the axial vector component in the leptonic coupling of the τ to hadrons. The branching ratio is given with BR(τ−→νπ−ρ0) =0.050±0.015. The total hadronic cross section agrees within errors with the quarksum rule including QCD‐corrections. The production and decay distributions of the decay J/ψ→f0γ have been measured and found to agree well with a QCD calculation based on the exchange of two gluons. |
