Aubert, B. et al. (2010) Measurements of Charged Current Lepton Universality and |V_{us}| Using Tau Lepton Decays to e^{-}ν[over ¯]_{e}ν_{τ}, μ^{-}ν[over ¯]_{μ}ν_{τ}, π^{-}ν_{τ}, and K^{-}ν_{τ}. Physical Review Letters, 105 (5). 051602. ISSN 0031-9007

Using 467  fb-1 of e+e- annihilation data collected with the BABAR detector, we measure B(τ-→μ-ν̅ μντ)/B(τ-→e-ν̅ eντ)=(0.9796±0.0016±0.0036), B(τ-→π-ντ)/B(τ-→e-ν̅ eντ)=(0.5945±0.0014±0.0061), and B(τ-→K-ντ)/B(τ-→e-ν̅ eντ)=(0.03882±0.00032±0.00057), where the uncertainties are statistical and systematic, respectively. From these precision τ measurements, we test the standard model assumption of μ-e and τ-μ charge current lepton universality and provide determinations of |Vus| experimentally independent of the decay of a kaon.

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