We report measurements of the ratios of branching fractions (Formula presented), where (Formula presented) denotes either an electron or a muon. These ratios test the universality of the charged-current weak interaction. The results are based on a 365 fb−1 data sample collected with the Belle II detector at the SuperKEKB − collider, which operates at a center-of-mass energy corresponding to the (Formula presented) resonance, just above the threshold for BB production. Signal candidates are reconstructed by selecting events in which the companion B meson from the (Formula presented) decay is identified in semileptonic modes. The tau lepton is reconstructed via its leptonic decays. We obtain (Formula presented) and (Formula presented), which are consistent with world average values. Accounting for the correlation between them, these values differ from the Standard Model expectation by a collective significance of 1.7 standard deviations.
Test of lepton flavor universality with measurements of R(D+) and R(D*+) using semileptonic B tagging at the Belle II experiment / Adachi, I.; Adamczyk, K.; Aggarwal, L.; Ahmed, H.; Aihara, H.; Akopov, N.; Alghamdi, S.; Alhakami, M.; Aloisio, A.; Althubiti, N.; Amos, K.; Angelsmark, M.; Anh Ky, N.; Antonioli, C.; Asner, D. m.; Atmacan, H.; Aushev, T.; Aushev, V.; Aversano, M.; Ayad, R.; Babu, V.; Bae, H.; Baghel, N. k.; Bahinipati, S.; Bambade, P.; Banerjee, Sw.; Bansal, S.; Barrett, M.; Bartl, M.; Baudot, J.; Beaubien, A.; Becherer, F.; Becker, J.; Bennett, J. v.; Bernlochner, F. u.; Bertacchi, V.; Bertemes, M.; Bertholet, E.; Bessner, M.; Bettarini, S.; Bhardwaj, V.; Bhuyan, B.; Bianchi, F.; Bilka, T.; Biswas, D.; Bobrov, A.; Bodrov, D.; Bolz, A.; Bondar, A.; Borah, J.; Boschetti, A.; Bozek, A.; Bračko, M.; Branchini, P.; Briere, R. a.; Browder, T. e.; Budano, A.; Bussino, S.; Campagna, Q.; Campajola, M.; Cao, L.; Casarosa, G.; Cecchi, C.; Cerasoli, J.; Chang, M. -C.; Chang, P.; Cheaib, R.; 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[10.1103/fmn3-h8fy]
Test of lepton flavor universality with measurements of R(D+) and R(D*+) using semileptonic B tagging at the Belle II experiment
Gabrielli, A.;Ganiev, E.;Ghosh, D.;Manfredi, R.;Mantovano, M.;Raiz, S.;Vitale, L.;
2025-01-01
Abstract
We report measurements of the ratios of branching fractions (Formula presented), where (Formula presented) denotes either an electron or a muon. These ratios test the universality of the charged-current weak interaction. The results are based on a 365 fb−1 data sample collected with the Belle II detector at the SuperKEKB − collider, which operates at a center-of-mass energy corresponding to the (Formula presented) resonance, just above the threshold for BB production. Signal candidates are reconstructed by selecting events in which the companion B meson from the (Formula presented) decay is identified in semileptonic modes. The tau lepton is reconstructed via its leptonic decays. We obtain (Formula presented) and (Formula presented), which are consistent with world average values. Accounting for the correlation between them, these values differ from the Standard Model expectation by a collective significance of 1.7 standard deviations.Pubblicazioni consigliate
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