Study of tau decays involving kaons, spectral functions and determination of the strange quark mass

Barate, R.; Collaboration, ALEPH

Study of tau decays involving kaons, spectral functions and determination of the strange quark mass

Authors

Description

All ALEPH measurements of branching ratios of tau decays involving kaons are summarized including a combination of results obtained with K^0_S and K^0_L detection. The decay dynamics are studied, leading to the determination of contributions from vector K^*(892) and K^{*}(1410), and axial-vector K_1(1270) and K_1(1400) resonances. Agreement with isospin symmetry is observed among the different final states. Under the hypothesis of the conserved vector current, the spectral function for the K\bar{K}πmode is compared with the corresponding cross section for low energy e^+e^- annihilation, yielding an axial-vector fraction of (94^{+6}_{-8})% for this mode. The branching ratio for tau decay into all strange final states is determined to be B(τ^-\to X^-(S=-1)ν_τ)=(28.7\pm1.2)\times 10^{-3}. The measured mass spectra of the strange tau decay modes are exploited to derive the S=-1 spectral function. A combination of strange and nonstrange spectral functions is used to determine the strange quark mass and nonperturbative contributions to the strange hadronic width. A method is developed to avoid the bad convergence of the spin zero hadronic component, with the result m_s(M_τ^2)=(176^{+46}_{-57}) MeV/c^2. The evolution down to 1 GeV gives m_s(1 {GeV}^2) = (234^{+61}_{-76}) MeV/c^2.
34 pages, 12 figures