Phenomenology of heavy quarks and quarkonium
In this thesis, we study the phenomenology of heavy quarks and heavy quarkonium. We study the strong decays of heavy mesons using an effective Lagrangian which incorporates heavy quark symmetry as well as spin-symmetry breaking corrections. Our predictions for the decay rates of excited D mesons are in much better agreement with experiment than previous calculations which included only leading order terms in the heavy quark expansion. We study perturbative QCD corrections to top quark decay, focusing on the problem of resolving scale ambiguities in leading order QCD calculations. The commonly used scale setting method of Brodsky, Lepage, and MacKenzie (BLM) gives misleading results when applied to the decay of top quarks into heavy bosons. We find that by performing an all order summation of higher order corrections, we achieve a better understanding of these top quark decays. Finally, we study the production of $J/\psi$ in collider experiments. The failure of traditional methods for calculating production cross sections of $J/\psi$ at hadron colliders has led to a newly hypothesized color-octet mechanism for quarkonium production. We calculate color-octet contributions to production of $J/\psi +\gamma$ in photon-proton collisions, and production of $J/\psi$ in lepton-proton collisions. Both processes provide clean signals for color-octet mechanisms which can be used to test quarkonium production theory.