Measurement of the branching ratio of B⁰ → D^*+ τ^- ν_τ relative to B⁰ → D^*+ ℓ^- ν_ℓ decays with a semileptonic tagging method

2016/03/22 by A. Abdesselam, Abdesselam, A., I. Adachi +541
Engineering · Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #Particle Accelerators and Free-Electron Lasers #Particle Detector Development and Performance #Particle physics theoretical and experimental studies

paper · pdf · doi:10.48550/arxiv.1603.06711

openalex publication_date 2016/03/22 · openalex created_date 2022/10/03 · openalex updated_date 2026/07/28

Abstract

We report a measurement of ratio \cal R(D^*) = \cal B(B⁰ → D^*+ τ^- ν_τ)/\cal B(B⁰ → D^*+ ℓ^- ν_ℓ), where ℓ denotes an electron or a muon. The results are based on a data sample containing 772×10⁶ BB pairs recorded at the Υ(4S) resonance with the Belle detector at the KEKB e⁺ e^- collider. We select a sample of B⁰ B⁰ pairs by reconstructing both B mesons in semileptonic decays to D^*∓ ℓ^±. We measure \cal R(D^*)= 0.302 ± 0.030(\rm stat) ± 0.011(\rm syst), which is within 1.6 σ of the Standard Model theoretical expectation, where σ is the standard deviation including systematic uncertainties.

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