HADRON SPECTRA FOR SEMILEPTONIC HEAVY-QUARK DECAY

We calculate the leading perturbative and power corrections to the had ronic invariant mass and energy spectra in semileptonic heavy hadron d ecays. We apply our results to the B system. Moments of the invariant mass spectrum, which vanish in the parton model, probe gluon bremsstra hlung and nonperturbative effects. Combining our results with recent d ata on B meson branching ratios, we obtain a lower bound <(Lambda)over bar>>410 MeV and an upper bound m(b)(pole)<4.89 GeV. The Brodsky-Lepa ge-Mackenzie scale-setting procedure suggests that higher order pertur bative corrections to the first moment of the hadronic invariant mass spectrum are small for bottom decay, and even tractable for charm deca y.