We determine the Cabibbo-Kobayashi-Maskawa matrix-element magnitude |Vcb| using B¯0→D*+ℓ-ν¯ℓ 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*+ℓ-ν¯ℓ)=(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 |Vcb| using B¯0→D*^+ℓ−ν¯ℓ decays with Belle II

Bettarini, S.;Casarosa, G.;Corona, L.;De Nuccio, M.;De Pietro, G.;Forti, F.;Lueck, T.;Martini, A.;Massaccesi, L.;Mondal, S.;Moneta, S.;Paladino, A.;Paoloni, E.;Rizzo, G.;Tenchini, F.;Zani, L.;
2023-01-01

Abstract

We determine the Cabibbo-Kobayashi-Maskawa matrix-element magnitude |Vcb| using B¯0→D*+ℓ-ν¯ℓ 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*+ℓ-ν¯ℓ)=(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
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/11568/1216484
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