B decays in the upsilon expansion

Theoretical predictions for B decay rates are rewritten in terms of the Υ(1S) meson mass instead of the b quark mass, using a modified perturbation expansion. The theoretical consistency of this expansion is shown both at low and high orders. Our method improves the behavior of the perturbation series for semileptonic and nonleptonic inclusive decay modes, as well as for exclusive decay form factors. The results are applied to the determination of the semileptonic B branching ratio, charm counting, the ratio of B→Xτ bar ν and B→Xe bar ν decay rates, and form factor ratios in B→D*e bar ν decay. We also comment on why it is not possible to separate perturbative and nonperturbative effects in QCD. thinsp copyright 1999 The American Physical Society