Studies of exclusive charmless semileptonique B decays and extraction of   |V_{ub}| at BABAR
  We report on recent measurements of the branching fractions (BFs) for the decay channels B^0 -> {\pi}^-\l^+{\nu}, B^+ -> {\pi}^0\l^+{\nu}, B^+ -> {\eta}\l^+{\nu}, B^+ -> {\eta}'\l^+{\nu}, B^0 -> {\rho}^-\l^+{\nu} and B^+ -> {\rho}^0\l^+{\nu}. We obtain very precise values of the total branching fractions for these decays, as well as partial branching fractions as a function of q^2 for the decay channels B^0 -> {\pi}^-\l^+{\nu}, B^+ -> {\eta}\l^+{\nu} and B^0 -> {\rho}^-\l^+{\nu}. In particular, we use the partial branching fractions of the B^0 -> {\pi}^-\l^+{\nu} decay channel and form-factor calculations to extract several values of |V_{ub}|. When we compared these values of |V_{ub}| to the one measured in inclusive semileptonic B decay, we find that two of them are consistent, within large theoretical uncertainties. 
Martin Simard
hep-ex