ISSN - 00319007, EISSN - 10797114, Physical Review Letters, 2006, vol. 97, p. -
Measurement of the B → nlv branching fraction and determination of |Vub| with tagged B mesons
We report a measurement of the B branching fraction based on 211fb-1 of data collected with the BABAR detector. We use samples of B0 and B+ mesons tagged by a second B meson reconstructed in a semileptonic or hadronic decay and combine the results assuming isospin symmetry to obtain B(B0-â., "+Î=(1.33Â±0.17statÂ±0.11syst)Ã-10-4. We determine the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element |Vub| by combining the partial branching fractions measured in ranges of the momentum transfer squared and theoretical calculations of the form factor. Using a recent lattice QCD calculation, we find |Vub|=(4.5Â±0. 5statÂ±0.3syst+0.7-0.5FF)Ã-10-3, where the last error is due to the normalization of the form factor. © 2006 The American Physical Society.