Measurement of exclusive branching fractions of hadronic one-prong tau decays

Abstract

We have measured the branching fractions for the hadronic τ decays, τ → π Knπ° ν (0≤ n ≤3), with the L3 detector at LEP. Multiphoton final states are analyzed using the fine-grained, high-resolution electromagnetic calorimeter. The decay channels are identified using a neural network method. The results are: BR(τ → π Kν ) = (11.82 ± 0.26 ± 0.43) %, BR(τ → π Kπ° ν) = (25.05 ± 0.35 ± 0.50) %, BR(τ → π K2π° ν) = (8.88 ± 0.37 ± 0.42) %, BR(τ → π K3πδ ν) = (1.70 ± 0.24 ± 0.38) %, where the first error quoted is statistical, the second systematic.