A sample of 365 fb−1 of (Formula presented) data collected by the Belle II experiment is used to measure the partial branching fractions of charmless semileptonic B meson decays and determine the magnitude of the Cabibbo-Kobayashi-Maskawa (CKM) matrix element Vub. Events containing a signal electron or muon l and a fully reconstructed hadronic B decay that constrains the signal kinematics are selected, while the rest of the event defines the hadronic system Xu associated with the signal. To discriminate the signal from the 50-times larger background originating from CKM-favored semileptonic B decays, a template fit is performed in both signal and control regions after applying an optimized selection. The partial branching fraction measured for lepton energies greater than 1 GeV in the signal B meson rest frame is (Formula presented). From this measurement, using the Gambino, Giordano, Ossola, Uraltsev theoretical framework, (Formula presented) is determined, where the uncertainties are experimental and theoretical, respectively. This value is consistent with the world average obtained from previous inclusive measurements. Different theoretical predictions and partial branching fractions measured in other phase-space regions, defined by additional selections on the Xu and leptonic system masses, are also used to determine jVubj. This allows for a comparison of the resulting values across theoretical frameworks and phase-space regions.

Abumusabh, M., Adachi, I., Adamczyk, K., Aggarwal, L., Ahmed, H., Ahn, Y., et al. (2026). Measurement of inclusive 𝐵 →𝑋𝑢⁢ℓ⁢𝜈 partial branching fractions and |𝑉𝑢⁢𝑏| at Belle II. PHYSICAL REVIEW D, 113(3), 1-23 [10.1103/59ws-zxbt].

Measurement of inclusive 𝐵 →𝑋𝑢⁢ℓ⁢𝜈 partial branching fractions and |𝑉𝑢⁢𝑏| at Belle II

Di Canto, A.;
2026

Abstract

A sample of 365 fb−1 of (Formula presented) data collected by the Belle II experiment is used to measure the partial branching fractions of charmless semileptonic B meson decays and determine the magnitude of the Cabibbo-Kobayashi-Maskawa (CKM) matrix element Vub. Events containing a signal electron or muon l and a fully reconstructed hadronic B decay that constrains the signal kinematics are selected, while the rest of the event defines the hadronic system Xu associated with the signal. To discriminate the signal from the 50-times larger background originating from CKM-favored semileptonic B decays, a template fit is performed in both signal and control regions after applying an optimized selection. The partial branching fraction measured for lepton energies greater than 1 GeV in the signal B meson rest frame is (Formula presented). From this measurement, using the Gambino, Giordano, Ossola, Uraltsev theoretical framework, (Formula presented) is determined, where the uncertainties are experimental and theoretical, respectively. This value is consistent with the world average obtained from previous inclusive measurements. Different theoretical predictions and partial branching fractions measured in other phase-space regions, defined by additional selections on the Xu and leptonic system masses, are also used to determine jVubj. This allows for a comparison of the resulting values across theoretical frameworks and phase-space regions.
2026
Abumusabh, M., Adachi, I., Adamczyk, K., Aggarwal, L., Ahmed, H., Ahn, Y., et al. (2026). Measurement of inclusive �� →����⁢ℓ⁢�� partial branching fractions and |����⁢��| at Belle II. PHYSICAL REVIEW D, 113(3), 1-23 [10.1103/59ws-zxbt].
Abumusabh, M.; Adachi, I.; Adamczyk, K.; Aggarwal, L.; Ahmed, H.; Ahn, Y.; Aihara, H.; Akopov, N.; Alghamdi, S.; Alhakami, M.; Aloisio, A.; Althubiti,...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/1083472
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