2004/08/16 by The BABAR Collaboration, B. Aubert, Aubert, B.
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #hep-ex
paper · pdf · doi:10.48550/arxiv.hep-ex/0408068
fix two typos and two figures
arxiv created 2005/01/04 · arxiv updated 2009/12/01
Based on 88 million Y(4S)->BB decays collected by the BaBar experiment at the PEP-II asymmetric-energy B factory at SLAC, we report preliminary results of four analyses which study in semileptonic charmless B decays, B->Xulnu and measure Vub. In events in which one B meson decay to a hadronic final state is fully reconstructed, the semileptonic decay of the second B meson is identified by the detection of a charged lepton. From both the spectrum of the mass of the hadronic system (mX) and the two-dimensional distribution of mX and q2 we derive the charmless semileptonic branching fraction and we extract Vub=(4.77± 0.28(stat.)± 0.25 (sys.)+0.65-0.39(theo.)) 10-3 and Vub=(4.92± 0.39(stat.)± 0.36 (sys.)± 0.46(theo.)) 10-3, respectively. We use the same sample to extract the true mX distribution for B->Xulnu events. Finally, we identify several exclusive charmless semileptonic B decays, and measure the branching fractions BR(B->pilnu) = (1.08 ± 0.28(stat.) ± 0.16(sys.))10-4 and BR(B-> rho lnu) = (2.57 ± 0.52(stat.) ± 0.59(sys.)) 10-4 using isospin and quark model constraints. We also set limits on BR(B- -> eta l nu), BR(B- -> eta' l nu), BR(B- -> a00 l nu), and BR(B0 -> a+0lnu).