Study of $b \to u l \nu$ Decays with an Inclusive Generator

A generator for inclusive b -> u l nu decays has been developed. Differentprescriptions have been applied to describe the kinematics of the b-quarkinside the hadron and the generation of the hadronic final states. Results arepresented with particular attention to the invariant mass of the hadronicsystem recoiling against the lepton and its resonance decomposition. Thesestudies are of special relevance for the extraction of Vub from semileptonic Bdecays at LEP and at B factories.