Determination of |Vub| from untagged B0π+ν decays using 2019-2021 Belle~II data

Sumitted to PubDB: 2022-10-11

Category: Conference papers and plots, Visibility: Public

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Authors Florian Bernlochner, Jochen Dingfelder, Svenja Granderath, Peter Lewis
Date Oct. 9, 2022
Belle II Number BELLE2-CONF-PH-2022-017
Abstract We present an analysis of the charmless semileptonic decay B0π+ν, where =e,μ, from 198.0 million pairs of BB¯ mesons recorded by the Belle~II detector at the SuperKEKB electron-positron collider. The decay is reconstructed without identifying the partner B meson. The partial branching fractions are measured independently for B0πe+νe and B0πμ+νμ as functions of q2 (momentum transfer squared), using 3896 B0πe+νe and 5466 B0πμ+νμ decays. The total branching fraction is found to be (1.426±0.056±0.125)×104 for B0π+ν decays, where the uncertainties are statistical and systematic, respectively. By fitting the measured partial branching fractions as functions of q2, together with constraints on the nonperturbative hadronic contribution from lattice QCD calculations, the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element Vub, (3.55±0.12±0.13±0.17)×103, is extracted. Here, the first uncertainty is statistical, the second is systematic and the third is theoretical.

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