Measurement of the B⁰ → D^*- ℓ⁺ ν_ℓ branching ratio and |V_cb| with a fully reconstructed accompanying B meson in 2019-2021 Belle II data

2023/01/11 by F. Abudinén, Abudinén, F., I. Adachi +680
Engineering · Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #Superconducting Materials and Applications

paper · pdf · doi:10.48550/arxiv.2301.04716

openalex publication_date 2023/01/11 · openalex created_date 2023/01/14 · openalex updated_date 2026/07/28

Abstract

We present a measurement of the B⁰ → D^*- ℓ⁺ ν_ℓ (ℓ=e,μ) branching ratio and of the CKM parameter |V_cb| using signal decays accompanied by a fully reconstructed B meson. The Belle II data set of electron-positron collisions at the Υ(4S) resonance, corresponding to 189.3 fb^-1 of integrated luminosity, is analyzed. With the Caprini-Lellouch-Neubert form factor parameterization, the parameters η_{\rm EW} F(1) |V_cb| and ρ² are extracted, where η_{\rm EW} is an electroweak correction, F(1) is a normalization factor and ρ² is a form factor shape parameter. We reconstruct 516 signal decays and thereby obtain B (B⁰ → D^*- ℓ⁺ ν_ℓ ) = (5.27 ± 0.22~\rm(stat) ± 0.38~\rm(syst)) %, η_EW F(1) |V_cb| × 10³ = 34.6 ± 1.8~\rm(stat) ± 1.7~\rm(syst), and ρ² = 0.94 ± 0.18~\rm(stat) ± 0.11~\rm(syst).

Related

• Measurement of the semileptonic B⁰ → D^*+ ℓ^- ν_ℓ branching fraction with fully reconstructed B meson decays and 34.6 fb^-1of Belle II data
• Precise determination of the CKM matrix element | V_cb| with B⁰ → D^{* +} ℓ^- ν_ℓ decays with hadronic tagging at Belle
• Determination of |V_cb| from B→ Dℓν decays using 2019-2021 Belle II data
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