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ISSN - 00319007, EISSN - 10797114, Physical Review Letters, 2008, vol. 100, p. -

Measurements of partial branching fractions for B̄→Xulν̄ and determination of |Vub|

Aubert B., Bona M., Boutigny D., Karyotakis Y., Lees J. P., Poireau V., Prudent X., Tisserand V., Zghiche A., Garra Tico J., Grauges E., Lopez L., Palano A., Pappagallo M., Eigen G., Stugu B., Sun L., Abrams G. S., Battaglia M., Brown D. N., Button-Shafer J., Cahn R. N., Groysman Y., Jacobsen R. G., Kadyk J. A., Kerth L. T., Kolomensky Yu G., Kukartsev G., Lopes Pegna D., Lynch G., Mir L. M., Orimoto T. J., Osipenkov I. L., Ronan M. T., Tackmann K., Tanabe T., Wenzel W. A., Del Amo Sanchez P., Hawkes C. M., Watson A. T., Koch H., Schroeder T., Walker D., Asgeirsson D. J., Cuhadar-Donszelmann T., Fulsom B. G., Hearty C., Mattison T. S., McKenna J. A., Barrett M., Khan A., Saleem M., Teodorescu L., Blinov V. E., Bukin A. D., Druzhinin V. P., Golubev V. B., Onuchin A. P., Serednyakov S. I., Skovpen Yu I., Solodov E. P., Todyshev K. Yu, Bondioli M., Curry S., Eschrich I., Kirkby D., Lankford A. J., Lund P., Mandelkern M., Martin E. C., Stoker D. P., Abachi S., Buchanan C., Foulkes S. D., Gary J. W., Liu F., Long O., Shen B. C., Vitug G. M., Zhang L., Paar H. P., Rahatlou S., Sharma V., Berryhill J. W., Campagnari C., Cunha A., Dahmes B., Hong T. M., Kovalskyi D., Richman J. D., Beck T. W., Eisner A. M., Flacco C. J., Heusch C. A., Kroseberg J., Lockman W. S., Schalk T., Schumm B. A., Seiden A., Wilson M. G.

We present partial branching fractions for inclusive charmless semileptonic B decays B̄→Xu ν̄, and the determination of the Cabibbo-Kobayashi-Maskawa matrix element |Vub|. The analysis is based on a sample of 383×106 Υ(4S) decays into BB̄ pairs collected with the BABAR detector at the SLAC PEP-II e+e- storage rings. We select events using the invariant mass MX of the hadronic system, the invariant mass squared, q2, of the lepton and neutrino pair, the kinematic variable P+, or one of their combinations. We then determine partial branching fractions in limited regions of phase space: ΔB=(1.18±0.09stat±0.07syst±0.01theor) ×10-3 (MX<1.55GeV/c2), ΔB=(0.95±0.10stat±0. 08syst±0.01theor)×10-3 (P+<0.66GeV/c), and ΔB=(0. 81±0.08stat±0.07syst±0.02theor)×10-3 (MX<1.7GeV/c2, q2>8GeV2/c4). Corresponding values of |Vub| are extracted using several theoretical calculations. © 2008 The American Physical Society.