We present a measurement of |V-ub| from a simultaneous study of the charmless semileptonic decays B-0 -> pi(-) l(+) nu(l) and B+ -> rho(0)l(+) nu(l), where l = e, mu. This measurement uses a data sample of 387 million BB meson pairs recorded by the Belle II detector at the SuperKEKB electron-positron collider between 2019 and 2022. The two decays are reconstructed without identifying the partner B mesons. We simultaneously measure the differential branching fractions of B-0 -> pi(-) l(+) nu(l) and B+ -> rho(0)l(+) nu(l) decays as functions of q(2) (momentum transfer squared). From these, we obtain total branching fractions B(B-0 -> pi(-) l(+)nu l) = (1.516 +/- 0.042(stat) +/- 0.059(syst)) x 10(-4) and B(B+ -> rho(0)l(+) nu(l)) = (1.625 +/- 0.079(stat) +/- 0.180(syst)) x 10(-4). By fitting the measured B-0 -> pi(-) l(+) nu(l) partial branching fractions as functions of q(2), together with constraints on the nonperturbative hadronic contribution from lattice QCD calculations, we obtain |V-ub| = (3.93 +/- 0.09 +/- 0.13 +/- 0.19) x 10(-3). Here, the first uncertainty is statistical, the second is systematic, and the third is theoretical.

Determination of jVubj from simultaneous measurements of untagged B0 → π −l+ νl and B+ → ρ0l+ νl decays

Gaz, A.;Stroili, R.;
2025

Abstract

We present a measurement of |V-ub| from a simultaneous study of the charmless semileptonic decays B-0 -> pi(-) l(+) nu(l) and B+ -> rho(0)l(+) nu(l), where l = e, mu. This measurement uses a data sample of 387 million BB meson pairs recorded by the Belle II detector at the SuperKEKB electron-positron collider between 2019 and 2022. The two decays are reconstructed without identifying the partner B mesons. We simultaneously measure the differential branching fractions of B-0 -> pi(-) l(+) nu(l) and B+ -> rho(0)l(+) nu(l) decays as functions of q(2) (momentum transfer squared). From these, we obtain total branching fractions B(B-0 -> pi(-) l(+)nu l) = (1.516 +/- 0.042(stat) +/- 0.059(syst)) x 10(-4) and B(B+ -> rho(0)l(+) nu(l)) = (1.625 +/- 0.079(stat) +/- 0.180(syst)) x 10(-4). By fitting the measured B-0 -> pi(-) l(+) nu(l) partial branching fractions as functions of q(2), together with constraints on the nonperturbative hadronic contribution from lattice QCD calculations, we obtain |V-ub| = (3.93 +/- 0.09 +/- 0.13 +/- 0.19) x 10(-3). Here, the first uncertainty is statistical, the second is systematic, and the third is theoretical.
2025
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/3594501
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