Reducing theoretical uncertainties in mb and λ1

We calculate general moments of the lepton energy spectrum in inclusive semileptonic B→Xclν-bar decay. Moments which allow the determination of mb1S and λ1 with theoretical uncertainties Δmb1S∼0.04 GeV and Δλ1∼0.05 GeV2 are presented. The short distance 1S mass is used to extract a mass parameter free of renormalon ambiguities. Moments which are insensitive to mb and λ1 and therefore test the size of the 1/mb3 matrix elements and the validity of the OPE are also presented. Finally, we give an expression for the total branching ratio with a lower cut on the lepton energy, which allows one to eliminate a source of model dependence in current determinations of |Vcb| from B→Xclν-bar decay