We report on determinations of |Vub| resulting from studies of the branching fraction and q2 distributions in exclusive semileptonic B decays that proceed via the b→u transition. Our data set consists of the 9.7×106 BB̄ meson pairs collected at the Y(4S) resonance with the CLEO II detector. We measure B(B0→π -ℓ+ν)=(1.33±0.18±0.11± 0.01±0.07)×10-4 and B(B0→ρ -ℓ+ν)=(2.17±0.34-0.54 +0.47±0.41 ±0.01)×10-4, where the errors are statistical, experimental systematic, systematic due to residual form-factor uncertainties in the signal, and systematic due to residual form-factor uncertainties in the cross-feed modes, respectively. We also find B(B+→ηℓ+ν)=(0.84±0.31± 0.16±0.09)×10-4, consistent with what is expected from the B→πℓν mode and quark model symmetries. We extract |V ub| using light-cone sum rules for 0≤q2<16GeV 2 and lattice QCD for 16 GeV2≤q2<q max2. Combining both intervals yields |V ub|=(3.24 ±0.22±0.13-0.39 +0.55-0.09)×10-3 for πℓν, and |V ub|=(3.00±0.210.35+0.29 -0.38+0.494±0.28)×10-3 for pfv, where the errors are statistical, experimental systematic, theoretical, and ρℓν form-factor shape, respectively. Our combined value from both decay modes is |Vub|=(3.17±0.17-0.17+ 0.16-0.39+0.53±0.03)×10 -3.
|Original language||English (US)|
|Number of pages||6480295|
|Journal||Physical Review D - Particles, Fields, Gravitation and Cosmology|
|State||Published - Oct 2003|
Bibliographical noteFunding Information:
This reeaswasrsupcporthed by the RussniFoandaution of Fundamental Research (Grant 96-03-33820), INAS T Project 96-922 and International Soros Science Educational Program (Grant a97-1151).