Determination of |V_cb| from B→ Dℓν decays using 2019-2021 Belle II data

2022/10/24 by Belle II Collaboration, Abudinén, F., Adachi, I. +590
#FOS: Physical sciences #High Energy Physics - Experiment (hep-ex)

paper · doi:10.48550/arxiv.2210.13143

Abstract

We present a determination of the magnitude of the Cabibbo-Kobayashi-Maskawa (CKM) matrix element V_cb using B→ Dℓν decays. The result is based on e⁺e^-→Υ(4S) data recorded by the Belle II detector corresponding to 189.2/fb of integrated luminosity. The semileptonic decays B⁰→ D^-(→ K⁺π^-π^-)ℓ⁺ν_ℓ and B⁺→ D⁰(→ K⁺π^-)ℓ⁺ν_ℓ are reconstructed, where ℓ is either electron or a muon. The second B meson in the Υ(4S) event is not explicitly reconstructed. Using the diamond-frame method, we determine the B meson four-momentum and thus the hadronic recoil. We extract the partial decay rates as functions of w and perform a fit to the decay form-factor and the CKM parameter |V_cb| using the BGL parameterization of the form factor and lattice QCD input from the FNAL/MILC and HPQCD collaborations. We obtain η_EW|V_cb|=(38.53± 1.15)× 10^-3, where η_EW is an electroweak correction, and the error accounts for theoretical and experimental sources of uncertainty.

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