The measurement of the CKM matrix element Vub using charmless semileptonic B decays, b-> u l v, gives a crucial constraint on the unitarity triangle. Franz Muheim and Dominic Lavin have begun studies of the best way to do this measurement at BaBar.

Sildes from a talk on Vub at BaBar, by Franz Muheim, can be found at http://www.slac.stanford.edu/~muheim/b2u