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Published November 1, 2012 | Published
Journal Article Open

Branching fraction and form-factor shape measurements of exclusive charmless semileptonic B decays, and determination of │V_(ub)│


We report the results of a study of the exclusive charmless semileptonic decays, B^0→π^-ℓ^+ν, B^+→π^0ℓ^+ν, B^+→ωℓ^+ν, B^+→ηℓ^+ν, and B^+→η′ℓ^+ν (ℓ=e or μ) undertaken with approximately 462×10^6 BB pairs collected at the Υ(4S) resonance with the BABAR detector. The analysis uses events in which the signal B decays are reconstructed with a loose neutrino reconstruction technique. We obtain partial branching fractions in several bins of q^2, the square of the momentum transferred to the lepton-neutrino pair, for B^0→π^-ℓ^+ν, B^+→π^0ℓ^+ν, B^+→ωℓ^+ν, and B^+→ηℓ^+ν. From these distributions, we extract the form-factor shapes f_+(q^2) and the total branching fractions B(B^0→π^-ℓ^+ν)=(1.45±0.04_(stat)±0.06_(syst))×10^(-4) (combined π^- and π^0 decay channels assuming isospin symmetry), B(B+→ωℓ+ν)=(1.19±0.16_(stat)±0.09_(syst))×10^(-4) and B(B^+→ηℓ^+ν)=(0.38±0.05_(stat)±0.05_(syst))×10^(-4). We also measure B(B^+→η′ℓ^+ν)=(0.24±0.08_(stat)±0.03_(syst))×10^(-4). We obtain values for the magnitude of the Cabibbo-Kobayashi-Maskawa (CKM) matrix element |V_(ub)| by direct comparison with three different QCD calculations in restricted q^2 ranges of B→πℓ^+ν decays. From a simultaneous fit to the experimental data over the full q^2 range and the FNAL/MILC lattice QCD predictions, we obtain |V_(ub)|=(3.25±0.31)×10^(-3), where the error is the combined experimental and theoretical uncertainty.

Additional Information

© 2012 American Physical Society. Received 7 August 2012; published 5 November 2012. We are grateful for the extraordinary contributions of our PEP-II colleagues in achieving the excellent luminosity and machine conditions that have made this work possible. The success of this project also relies critically on the expertise and dedication of the computing organizations that support BABAR. The collaborating institutions wish to thank SLAC for its support and the kind hospitality extended to them. This work is supported by the U.S. Department of Energy and National Science Foundation, the Natural Sciences and Engineering Research Council (Canada), the Commissariat à l'Energie Atomique and Institut National de Physique Nucléaire et de Physique des Particules (France), the Bundesministerium für Bildung und Forschung and Deutsche Forschungsgemeinschaft (Germany), the Istituto Nazionale di Fisica Nucleare (Italy), the Foundation for Fundamental Research on Matter (The Netherlands), the Research Council of Norway, the Ministry of Education and Science of the Russian Federation, Ministerio de Ciencia e Innovaciόn (Spain), and the Science and Technology Facilities Council (United Kingdom). Individuals have received support from the Marie Curie IEF program (European Union), the A. P. Sloan Foundation (USA), and the Binational Science Foundation (USA-Israel).

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Published - PhysRevD.86.092004.pdf


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