We report measurements of the ratios of branching fractions R⁡(D⁽*⁾⁺)=B(¯B⁰→D⁽*⁾⁺⁢t⁻¯vₜ)/B⁡(¯B⁰→D⁽*⁾⁺⁢l⁻⁢¯vₗ), where l 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 e⁺e⁻ collider, which operates at a center-of-mass energy corresponding to the (Formula presented) resonance, just above the threshold for BB̄ 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 τ lepton is reconstructed via its leptonic decays. We obtain R⁡(D⁺)=0.418+0.075−0.073⁢(stat)+0.049−0.056⁢(syst) and R(D*⁺)=0.306+0.035−0.033⁢(stat)+0.016−0.018⁢(syst), 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., et al.. - In: PHYSICAL REVIEW D. - ISSN 2470-0010. - 112:3(2025). [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

Aloisio A.;Budano A.;Campajola M.;De Nardo G.;Di Capua F.;Gaudino G.;Giordano R.;Merola M.;Mirra M.;
2025

Abstract

We report measurements of the ratios of branching fractions R⁡(D⁽*⁾⁺)=B(¯B⁰→D⁽*⁾⁺⁢t⁻¯vₜ)/B⁡(¯B⁰→D⁽*⁾⁺⁢l⁻⁢¯vₗ), where l 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 e⁺e⁻ collider, which operates at a center-of-mass energy corresponding to the (Formula presented) resonance, just above the threshold for BB̄ 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 τ lepton is reconstructed via its leptonic decays. We obtain R⁡(D⁺)=0.418+0.075−0.073⁢(stat)+0.049−0.056⁢(syst) and R(D*⁺)=0.306+0.035−0.033⁢(stat)+0.016−0.018⁢(syst), 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.
2025
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., et al.. - In: PHYSICAL REVIEW D. - ISSN 2470-0010. - 112:3(2025). [10.1103/fmn3-h8fy]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11588/1043125
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