Using a data sample of e^{+}e^{-} collisions corresponding to an integrated luminosity of 567 pb^{-1} collected at a center-of-mass energy of sqrt[s]=4.6 GeV with the BESIII detector, we measure the absolute branching fraction of the inclusive semileptonic Λ_{c}^{+} decay with a double-tag method. We obtain B(Λ_{c}^{+}→Xe^{+}ν_{e})=(3.95±0.34±0.09)%, where the first uncertainty is statistical and the second systematic. Using the known Λ_{c}^{+} lifetime and the charge-averaged semileptonic decay width of nonstrange charmed mesons (D^{0} and D^{+}), we obtain the ratio of the inclusive semileptonic decay widths Γ(Λ_{c}^{+}→Xe^{+}ν_{e})/Γ[over ¯](D→Xe^{+}ν_{e})=1.26±0.12.
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http://dx.doi.org/10.1103/PhysRevLett.121.251801 | DOI Listing |
We measure the complete set of angular coefficients J_{i} for exclusive B[over ¯]→D^{*}ℓν[over ¯]_{ℓ} decays (ℓ=e, μ). Our analysis uses the full 711 fb^{-1} Belle dataset with hadronic tag-side reconstruction. The results allow us to extract the form factors describing the B[over ¯]→D^{*} transition and the Cabibbo-Kobayashi-Maskawa matrix element |V_{cb}|.
View Article and Find Full Text PDFPhys Rev Lett
March 2024
State Key Laboratory of Particle Detection and Electronics, Beijing 100049, Hefei 230026, People's Republic of China.
By analyzing 7.33 fb^{-1} of e^{+}e^{-} annihilation data collected at center-of-mass energies between 4.128 and 4.
View Article and Find Full Text PDFWe 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.
View Article and Find Full Text PDFThe first measurements of differential branching fractions of inclusive semileptonic B→X_{u}ℓ^{+}ν_{ℓ} decays are performed using the full Belle data set of 711 fb^{-1} of integrated luminosity at the ϒ(4S) resonance and for ℓ=e, μ. With the availability of these measurements, new avenues for future shape-function model-independent determinations of the Cabibbo-Kobayashi-Maskawa matrix element |V_{ub}| can be pursued to gain new insights in the existing tension with respect to exclusive determinations. The differential branching fractions are reported as a function of the lepton energy, the four-momentum-transfer squared, light-cone momenta, the hadronic mass, and the hadronic mass squared.
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