We present the first measurement of the ratio of branching fractions of inclusive semileptonic B-meson decays, R(X_{e/μ})=B(B→Xeν)/B(B→Xμν), a precision test of electron-muon universality, using data corresponding to 189  fb^{-1} from electron-positron collisions collected with the Belle II detector. In events where the partner B meson is fully reconstructed, we use fits to the lepton momentum spectra above 1.3  GeV/c to obtain R(X_{e/μ})=1.007±0.009(stat)±0.019(syst), which is the most precise lepton-universality test of its kind and agrees with the standard-model expectation.

Test of Light-Lepton Universality in the Rates of Inclusive Semileptonic B -Meson Decays at Belle II / Aggarwal, L., Ahmed, H., Aihara, H., Akopov, N., Aloisio, A., Anh Ky, N., Asner, D. M., Atmacan, H., Aushev, T., Aushev, V., Bae, H., Bahinipati, S., Bambade, P., Banerjee, Sw., Bansal, S., Barrett, M., Baudot, J., Bauer, M., Baur, A., Beaubien, A., et al.. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - STAMPA. - 131/2023:5(2023), pp. 051804.1-051804.7. [10.1103/PhysRevLett.131.051804]

Test of Light-Lepton Universality in the Rates of Inclusive Semileptonic B -Meson Decays at Belle II

Gabrielli, A.;Ganiev, E.;Manfredi, R.;Mantovano, M.;Vitale, L.;
2023-01-01

Abstract

We present the first measurement of the ratio of branching fractions of inclusive semileptonic B-meson decays, R(X_{e/μ})=B(B→Xeν)/B(B→Xμν), a precision test of electron-muon universality, using data corresponding to 189  fb^{-1} from electron-positron collisions collected with the Belle II detector. In events where the partner B meson is fully reconstructed, we use fits to the lepton momentum spectra above 1.3  GeV/c to obtain R(X_{e/μ})=1.007±0.009(stat)±0.019(syst), which is the most precise lepton-universality test of its kind and agrees with the standard-model expectation.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11368/3068802
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