Measurement of R(D) and R(D^*) with a semileptonic tagging method

2019/11/18 by G. Caria, Caria, Giacomo
Engineering · Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #Particle Accelerators and Free-Electron Lasers #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions

paper · pdf · doi:10.48550/arxiv.1911.07686

openalex publication_date 2019/11/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

We report a measurement of the ratios of branching fractions R(D^(*)) = \cal B(B → D^(*) τ^- ν_τ)/\cal B(B → D^(*) ℓ^- ν_ℓ) where ℓ denotes an electron or a muon. The results are based on a data sample containing 772 × 10⁶ BB events recorded at the Υ(4S) resonance with the Belle detector at the KEKB e⁺ e^- collider. The tag-side B meson is reconstructed in a semileptonic decay mode, and the signal-side τ is reconstructed in a purely leptonic decay. The results are R(D) = 0.307 ± 0.037 ± 0.016 and R(D^*)=0.283 ± 0.018 ± 0.014, where the first uncertainties are statistical and the second are systematic. These results are in agreement with the Standard Model predictions within 0.2 and 1.1 standard deviations, respectively.

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