Determination of |Vub| from the measurement of B to X l nu Branching Fractions and Form Factors at BaBar
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David Côté, Université de Montréal, S. Brunet (UdeM), J.C. Dingfelder (SLAC), 
M. Simard (UdeM), B.F.Viaud (UdeM) and P. Taras (UdeM)

BaBar's Runs 1-4 data sample will contain approximately 480 million B
decays and several tens of thousands of each of the lower mass
exclusive B to X l nu decays. The combination of this unprecedented
large data set with an improved version of the "neutrino
reconstruction" technique will allow a measurement of the B to X l nu
branching fractions and form factors in a model independent way. This
is achieved by maximizing the signal extraction efficiency at the cost
of accepting more of the well-understood B to Xc l nu and continuum
backgrounds. The cross-feeds arising from the various Xu l nu decays
will be taken into account by a simultaneous fit of all the lower mass
exclusive B to Xu l nu branching fractions and form factors. These
will provide valuable information about QCD and semileptonic b to u l
nu decays. By excluding or validating specific form factor models, the
theoretical uncertainty in determining |Vub| from exclusive B to Xu l
nu decays will be greatly reduced and should be competitive with the
most precise measurements to date. This would be specially true in the
framework of improvements in unquenched lattice QCD. We will present
an overview of this complex but very promising analysis that is well
underway as well as some preliminary results.