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.
Aggarwal, L., Ahmed, H., Aihara, H., Akopov, N., Aloisio, A., Anh Ky, N., et al. (2023). Test of Light-Lepton Universality in the Rates of Inclusive Semileptonic B-Meson Decays at Belle II. PHYSICAL REVIEW LETTERS, 131(5), 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
Bernieri, EMembro del Collaboration Group
;Budano, AMembro del Collaboration Group
;Bussino, SMembro del Collaboration Group
;De Pietro, GMembro del Collaboration Group
;Laurenza, MMembro del Collaboration Group
;Martellini, CMembro del Collaboration Group
;Martini, AMembro del Collaboration Group
;
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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
