We determine the Cabibbo-Kobayashi-Maskawa matrix-element magnitude |Vcb| using B¯0→D∗+-ν¯ decays reconstructed in 189 fb-1 of collision data collected by the Belle II experiment, located at the SuperKEKB e+e- collider. Partial decay rates are reported as functions of the recoil parameter w and three decay angles separately for electron and muon final states. We obtain |Vcb| using the Boyd-Grinstein-Lebed and Caprini-Lellouch-Neubert parametrizations, and find |Vcb|BGL=(40.57±0.31±0.95±0.58)×10-3 and |Vcb|CLN=(40.13±0.27±0.93±0.58)×10-3 with the uncertainties denoting statistical components, systematic components, and components from the lattice QCD input, respectively. The branching fraction is measured to be B(B¯0→D∗+-ν¯)=(4.922±0.023±0.220)%. The ratio of branching fractions for electron and muon final states is found to be 0.998±0.009±0.020. In addition, we determine the forward-backward angular asymmetry and the D∗+ longitudinal polarization fractions. All results are compatible with lepton-flavor universality in the Standard Model.

Determination of jVcbj using B ̄ 0 → D + l − ν ̄l decays with Belle II

Bianchi, F.;Das, S.;Destefanis, M.;Maggiora, M.;Spataro, S.;
2023-01-01

Abstract

We determine the Cabibbo-Kobayashi-Maskawa matrix-element magnitude |Vcb| using B¯0→D∗+-ν¯ decays reconstructed in 189 fb-1 of collision data collected by the Belle II experiment, located at the SuperKEKB e+e- collider. Partial decay rates are reported as functions of the recoil parameter w and three decay angles separately for electron and muon final states. We obtain |Vcb| using the Boyd-Grinstein-Lebed and Caprini-Lellouch-Neubert parametrizations, and find |Vcb|BGL=(40.57±0.31±0.95±0.58)×10-3 and |Vcb|CLN=(40.13±0.27±0.93±0.58)×10-3 with the uncertainties denoting statistical components, systematic components, and components from the lattice QCD input, respectively. The branching fraction is measured to be B(B¯0→D∗+-ν¯)=(4.922±0.023±0.220)%. The ratio of branching fractions for electron and muon final states is found to be 0.998±0.009±0.020. In addition, we determine the forward-backward angular asymmetry and the D∗+ longitudinal polarization fractions. All results are compatible with lepton-flavor universality in the Standard Model.
2023
108
9
092013-1
092013-26
https://journals.aps.org/prd/abstract/10.1103/PhysRevD.108.092013
Cabibbo–Kobayashi–Maskawa matrix, Electroweak interaction, Form factors
Adachi, I.; Aggarwal, L.; Ahmed, H.; Aihara, H.; Akopov, N.; Aloisio, A.; Anh Ky, N.; Asner, D. M.; Atmacan, H.; Aushev, T.; Aushev, V.; Aversano, M.;...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/2069018
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