Thursday, June 13, 2013

1306.2781 (Belle Collaboration et al.)

Study of Exclusive B->X_u l nu Decays and Extraction of |V_{ub}| using
Full Reconstruction Tagging at the Belle Experiment

Belle Collaboration, A. Sibidanov, K. E. Varvell, I. Adachi, H. Aihara, D. M. Asner, V. Aulchenko, T. Aushev, A. M. Bakich, A. Bala, A. Bozek, M. Bračko, T. E. Browder, V. Chekelian, P. Chen, B. G. Cheon, K. Chilikin, R. Chistov, I. -S. Cho, K. Cho, V. Chobanova, Y. Choi, D. Cinabro, J. Dalseno, M. Danilov, J. Dingfelder, Z. Doležal, Z. Drásal, A. Drutskoy, D. Dutta, S. Eidelman, D. Epifanov, H. Farhat, J. E. Fast, T. Ferber, A. Frey, V. Gaur, S. Ganguly, R. Gillard, Y. M. Goh, B. Golob, J. Haba, H. Hayashii, Y. Hoshi, W. -S. Hou, H. J. Hyun, T. Iijima, A. Ishikawa, R. Itoh, Y. Iwasaki, T. Julius, D. H. Kah, J. H. Kang, T. Kawasaki, C. Kiesling, D. Y. Kim, H. J. Kim, J. B. Kim, J. H. Kim, K. T. Kim, Y. J. Kim, J. Klucar, B. R. Ko, P. Kodyš, S. Korpar, P. Križan, P. Krokovny, B. Kronenbitter, T. Kuhr, A. Kuzmin, Y. -J. Kwon, S. -H. Lee, J. Li, Y. Li, J. Libby, Y. Liu, D. Liventsev, P. Lukin, D. Matvienko, K. Miyabayashi, H. Miyata, G. B. Mohanty, A. Moll, R. Mussa, Y. Nagasaka, E. Nakano, M. Nakao, Z. Natkaniec, M. Nayak, E. Nedelkovska, C. Ng, N. K. Nisar, S. Nishida, O. Nitoh, T. Nozaki, S. Ogawa, S. Okuno, S. L. Olsen, C. Oswald, H. Park, H. K. Park, T. K. Pedlar, R. Pestotnik, M. Petrič, L. E. Piilonen, M. Ritter, M. Röhrken, A. Rostomyan, S. Ryu, H. Sahoo, T. Saito, Y. Sakai, S. Sandilya, L. Santelj, T. Sanuki, Y. Sato, V. Savinov, O. Schneider, G. Schnell, C. Schwanda, K. Senyo, O. Seon, M. E. Sevior, M. Shapkin, V. Shebalin, C. P. Shen, T. -A. Shibata, J. -G. Shiu, F. Simon, P. Smerkol, Y. -S. Sohn, E. Solovieva, S. Stanič, M. Starič, M. Steder, M. Sumihama, K. Sumisawa, T. Sumiyoshi, G. Tatishvili, Y. Teramoto, K. Trabelsi, T. Tsuboyama, M. Uchida, S. Uehara, T. Uglov, Y. Unno, S. Uno, P. Urquijo, Y. Ushiroda, S. E. Vahsen, C. Van Hulse, P. Vanhoefer, G. Varner, V. Vorobyev, M. N. Wagner, C. H. Wang, P. Wang, M. Watanabe, Y. Watanabe, K. M. Williams, E. Won, B. D. Yabsley, Y. Yamashita, S. Yashchenko, Y. Yook, Z. P. Zhang, V. Zhilich, V. Zhulanov, A. Zupanc
We report the results of a study of the exclusive semileptonic decays B->pi0lnu, B->pi+lnu, B->rho0lnu, B->rho+lnu and B->omegalnu, where l represents an electron or a muon. The events are tagged by fully reconstructing a second B meson in the event in a hadronic decay mode. The measured branching fractions are Br(B->pi0lnu) = (0.80 +- 0.08 +- 0.04)x10^-4, Br(B->pi+lnu) = (1.49 +- 0.09 +- 0.07)x10^-4, Br(B->rho0lnu) = (1.83 +- 0.10 +- 0.10)x10^-4, Br(B->rho+lnu) = (3.22 +- 0.27 +- 0.24)x10^-4, and Br(B->omegalnu) =(1.07 +- 0.16 +- 0.07)x10^-4, where the first error is statistical and the second one is systematic. The obtained branching fractions are inclusive of soft photon emission. We also determine the branching fractions as a function of the 4-momentum transfer squared to the leptonic system q^2=(p_l+p_nu)^2, where p_l and p_nu are the lepton and neutrino 4-momenta, respectively. Using the pion modes, a recent LCSR calculation, lattice QCD results and a model-independent description of the hadronic form factor, a value of the CKM matrix element |V_{ub}| = (3.52 +- 0.29)x10^-3 is extracted. For the first time, a charmless state with invariant mass greater than 1 GeV/c^2, which might be dominated by the decay B->f2lnu, is observed. These results are obtained from a 711 1/fb data sample that contains 772 millions BB pairs, collected near the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e^+ e^- collider.
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