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arXiv · 1306.3353

Evidence for Semileptonic B- to p pbar l nubar Decays

K. -J. Tien·M. -Z. Wang·I. Adachi·H. Aihara·D. M. Asner·V. Aulchenko·T. Aushev·A. M. Bakich·A. Bala·B. Bhuyan·A. Bozek·M. Bračko·T. E. Browder·P. Chang·V. Chekelian·A. Chen·P. Chen·B. G. Cheon·K. Chilikin·R. Chistov·I. -S. Cho·K. Cho·V. Chobanova·Y. Choi·D. Cinabro·J. Dalseno·M. Danilov·Z. Doležal·Z. Drásal·D. Dutta·S. Eidelman·H. Farhat·J. E. Fast·T. Ferber·V. Gaur·S. Ganguly·R. Gillard·Y. M. Goh·B. Golob·J. Haba·H. Hayashii·Y. Horii·Y. Hoshi·W. -S. Hou·Y. B. Hsiung·M. Huschle·H. J. Hyun·T. Iijima·A. Ishikawa·R. Itoh·Y. Iwasaki·T. Julius·D. H. Kah·J. H. Kang·E. Kato·T. Kawasaki·H. Kichimi·C. Kiesling·D. Y. Kim·H. J. Kim·J. B. Kim·J. H. Kim·Y. J. Kim·J. Klucar·B. R. Ko·P. Kodyš·S. Korpar·P. Križan·P. Krokovny·B. Kronenbitter·T. Kuhr·T. Kumita·A. Kuzmin·Y. -J. Kwon·S. -H. Lee·J. Li·Y. Li·J. Libby·C. Liu·Y. Liu·D. Liventsev·P. Lukin·K. Miyabayashi·H. Miyata·G. B. Mohanty·A. Moll·R. Mussa·E. Nakano·M. Nakao·Z. Natkaniec·M. Nayak·E. Nedelkovska·C. Ng·N. K. Nisar·S. Nishida·O. Nitoh·S. Ogawa·S. Okuno·S. L. Olsen·W. Ostrowicz
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Abstract

We find evidence for the semileptonic baryonic decay $B^-\to p\bar p\ell^-\bar\nu_\ell$ ($\ell=e,\mu$), based on a data sample of 772 million $B\bar B$ pairs collected at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy electron-positron collider. A neural-network based hadronic $B$-meson tagging method is used in this study. The branching fraction of $B^-\to p\bar p\ell^-\bar\nu_\ell$ is measured to be $(5.8^{+2.4}_{-2.1}\textrm{(stat.)}\pm 0.9\textrm{(syst.)})\times 10^{-6}$ with a significance of 3.2$\sigma$, where lepton universality is assumed. We also estimate the corresponding upper limit: $\mathcal{B}(B^-\to p\bar p\ell^-\bar\nu_\ell) < 9.6\times 10^{-6}$ at the 90% confidence level. This measurement helps constrain the baryonic transition form factor in B decays.

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K. -J. Tien, M. -Z. Wang, I. Adachi, H. Aihara, D. M. Asner, V. Aulchenko, T. Aushev, A. M. Bakich, A. Bala, B. Bhuyan, A. Bozek, M. Bračko, T. E. Browder, P. Chang, V. Chekelian, A. Chen, P. Chen, B. G. Cheon, K. Chilikin, R. Chistov, I. -S. Cho, K. Cho, V. Chobanova, Y. Choi, D. Cinabro, J. Dalseno, M. Danilov, Z. Doležal, Z. Drásal, D. Dutta, S. Eidelman, H. Farhat, J. E. Fast, T. Ferber, V. Gaur, S. Ganguly, R. Gillard, Y. M. Goh, B. Golob, J. Haba, H. Hayashii, Y. Horii, Y. Hoshi, W. -S. Hou, Y. B. Hsiung, M. Huschle, H. J. Hyun, T. Iijima, A. Ishikawa, R. Itoh, Y. Iwasaki, T. Julius, D. H. Kah, J. H. Kang, E. Kato, T. Kawasaki, H. Kichimi, C. Kiesling, D. Y. Kim, H. J. Kim, J. B. Kim, J. H. Kim, Y. J. Kim, J. Klucar, B. R. Ko, P. Kodyš, S. Korpar, P. Križan, P. Krokovny, B. Kronenbitter, T. Kuhr, T. Kumita, A. Kuzmin, Y. -J. Kwon, S. -H. Lee, J. Li, Y. Li, J. Libby, C. Liu, Y. Liu, D. Liventsev, P. Lukin, K. Miyabayashi, H. Miyata, G. B. Mohanty, A. Moll, R. Mussa, E. Nakano, M. Nakao, Z. Natkaniec, M. Nayak, E. Nedelkovska, C. Ng, N. K. Nisar, S. Nishida, O. Nitoh, S. Ogawa, S. Okuno, S. L. Olsen, W. Ostrowicz. 2013-06-14. Evidence for Semileptonic B- to p pbar l nubar Decays. https://doi.org/10.1103/physrevd.89.011101

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