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

All ALEPH measurements of branching ratios of tau decays involving kaons are summarized including a combination of results obtained with K(s)(0) and K(L)(0) detection. The decay dynamics are stud led, 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(K)over bar pi> mode is compared with the corresponding cross section for low energy e(+)e(-) annihilation, yielding an axial-vector fraction of (94(-8)(+6))% for this mode. The branching ratio for tau decay into all strange final states is determined to be B(tau(-) --> X(-) (S = -1)nu(tau)) = (28.7 +/- 1.2) x 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(tau)(2)) = (176(-57)(+46)) MeV/c(2). The evolution down to 1 GeV gives m(s)(1 GeV(2)) = (234(-76)(+61)) MeV/c(2).