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

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Date

2023-08-02, 2023-08-02

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Publisher

American Physical Society

Abstract

We present the first measurement of the ratio of branching fractions of inclusive semileptonic B-meson decays, R(Xe/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(Xe/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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Keywords

Science & Technology, Physical Sciences, Physics, Multidisciplinary, Physics, MONTE-CARLO, HEAVY, Belle II Collaboration, 5106 Nuclear and Plasma Physics, 5107 Particle and High Energy Physics, 4902 Mathematical Physics, 49 Mathematical Sciences, 51 Physical Sciences, 40 Engineering

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