Measurement of the spectral function for the $τ^-\to K^-K_Sν_τ$ decay in BABAR experiment

The decay \mathbf{\tau^{-}\to K^{-}K_S\nu_{\tau}}𝛕−→𝐊−𝐊𝐒𝛎𝛕 has been studied using \mathbf{430\times10^6 ~ e^+e^-\to \tau^+\tau^-}430×106𝐞+𝐞−→𝛕+𝛕− events produced at a center-of-mass energy around 10.6 GeV at the PEP-II collider and studied with the BABAR detector. The mass spectrum of the \mathbf{K^{-}K_S}𝐊−𝐊𝐒 system has been measured and the spectral function has been obtained. The measured branching fraction \mathbf{{\cal B}(\tau^{-}\to K^{-}K_S\nu_{\tau})= (0.739\pm 0.011(\rm stat.)\pm 0.020(\rm syst.))}\mathbf{\times 10^{-3}}×10−3 is found to be in agreement with earlier measurements.

Measurement of the branching fractions of the decays τ−→ K−nπ0ντ (n = 0, 1, 2, 3) and τ−→ π−nπ0ντ (n = 3, 4) by BABAR

We report preliminary measurements of the branching fractions of the decays τ−→ K−nπ0 ντ (n = 0, 1, 2, 3) and τ−→ π−nπ0ντ (n = 3, 4), excluding the contributions that proceed through the decay of intermediate K0 and η mesons. The measurements are based on a data sample of 435 million τ pairs produced in e+e− collisions at and near the γ(4S) peak and collected with the BABAR detector in 1999–2008. The measured branching fractions are B(τ−→ K− ντ) = (7.174±0.033±0.213)×10−3, B(τ−→ K−π0ντ) = (5.054± 0.021 ± 0.148) × 10−3, B(τ−→ K−2π0ντ) = (6.151 ± 0.117 ± 0.338) × 10−4, B(τ−→ K−3π0ντ) = (1.246 ± 0.164 ± 0.238) × 10−4, B(τ−→ π−3π0ντ) = (1.168 ±0.006 ±0.038) ×10−2, B(τ−→ π−4π0ντ) = (9.020 ±0.400 ±0.652) × 10−4, where the ?rst uncertainty is statistical and the second one systematic.

Study of ϒ(1S) radiative decays to γπ+π- and γK+K-

We study the ϒ(1S) radiative decays to γπ+π- and γK+K- using data recorded with the BABAR detector operating at the SLAC PEP-II asymmetric-energy e+e- collider at center-of-mass energies at the ϒ(2S) and ϒ(3S) resonances. The ϒ(1S) resonance is reconstructed from the decay ϒ(nS) → π+π-ϒ(1S), n = 2, 3.