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Scientific article
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English

Measurement of the tau branching fractions into leptons

ContributorsL3 Collaboration
Published inPhysics letters. B, vol. 507, no. 1-4, p. 47-60
Publication date2001
Abstract

Using data collected with the L3 detector near the Z resonance, corresponding to an integrated luminosity of 150pb-1, the branching fractions of the tau lepton into electron and muon are measured to be B(tau->e nu nu) = (17.806 +- 0.104 (stat.) +- 0.076 (syst.)) %, B(tau->mu nu nu) = (17.342 +- 0.110 (stat.) +- 0.067 (syst.)) %. From these results the ratio of the charged current coupling constants of the muon and the electron is determined to be g_mu/g_e = 1.0007 +- 0.0051. Assuming electron-muon universality, the Fermi constant is measured in tau lepton decays as G_F = (1.1616 +- 0.0058) 10^{-5} GeV^{-2}. Furthermore, the coupling constant of the strong interaction at the tau mass scale is obtained as alpha_s(m_tau^2) = 0.322 +- 0.009 (exp.) +- 0.015 (theory).

Citation (ISO format)
L3 Collaboration. Measurement of the tau branching fractions into leptons. In: Physics letters. B, 2001, vol. 507, n° 1-4, p. 47–60. doi: 10.1016/S0370-2693(01)00294-5
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ISSN of the journal0370-2693
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