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).

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

ROLANDI, LUIGI;LIGABUE, FRANCO;LUSIANI, Alberto
Membro del Collaboration Group
;
1999

Abstract

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 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).
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11384/1743
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