Impact on | $V_{us}$| from decays: New BaBar results on $\tau^- \to K^- n \pi^0\nu_{\tau}$(n = 0, 1, 2, 3) and $\tau^- \to \pi^- n \pi^0 \nu_{\tau}$(n = 3, 4)

Abstract

This paper reports preliminary measurements of the branching fractions of τ hadronic decays in channels with one negative kaon or pion and multiple π0’s: τ − → K − nπ0ντ (with n = 0, 1, 2, 3) and τ − → π − nπ0ντ (with n = 3, 4). These measurements are of fundamental importance for the precise determination of the |Vus| Cabibbo-Kobahashi-Maskawa matrix element. Based on a data sample of about 435 million τ pairs produced in e+e − collisions at and near the Υ(4S) peak, collected by the BABAR experiment in about ten years of data taking, the following values have been obtained: B(τ − → K − ντ) = (7.174±0.033stat ±0.213sys)×10 −3, B(τ − → K − π0ντ) = (5.054 ± 0.021stat ± 0.148sys) × 10 −3, B(τ − → K − 2π0ντ) = (6.151 ± 0.117stat ± 0.338sys) × 10 −4, B(τ − → K − 3π0ντ) = (1.246 ± 0.164stat ± 0.238sys) × 10 −4, B(τ − → π − 3π0ντ) = (1.168 ± 0.006stat ± 0.038sys) × 10 −2 and B(τ − → π − 4π0ντ) = (9.020 ± 0.400stat ± 0.652sys) × 10 −4.