Tau decays into Kaons in DELPHI

Abstract

Exclusive and inclusive branching ratios of several τ decays with kaons in the final state have been measured using data collected with the DELPHI detector. Charged kaons are tagged over a large momentum range by the Ring Imaging Cherenkov detector, and the secondary vertices of Ks0 decays into charged pions are reconstructed. The result BR(τ → Kν) = (0.85 ± 0.18) % is in agreement with the Standard Model prediction based on τ—μ—e universality. The branching ratio BR(τ → K*ν) = (1.71 ±0.36) % is a combination of two independent measurements in the π±Ks0 and the K±π0 mode. Also inclusive branching ratio were measured: BR(τ → Kν ≥ 0 neutrals) = (1.54 ± 0.24)%, BR(τ → Kν ≥ 1 neutrals) = (0.64 ± 0.24)% and BR(τ → Ks0X±ν) = (0.99 ± 0.19) %. The uncertainties of all results are dominated by statistics.