IMPROVED NONRELATIVISTIC QCD FOR HEAVY-QUARK PHYSICS

We construct an improved version of nonrelativistic QCD for use in lattice simulations of heavy-quark physics, with the goal of reducing systematic errors from all sources to below 10%. We develop power-counting rules to assess the importance of the various operators in the action and compute all leading-order corrections required by relativity and finite lattice spacing. We discuss radiative corrections to tree-level coupling constants, presenting a procedure that effectively resums the largest such corrections to all orders in perturbation theory. Finally, we comment on the size of nonperturbative contributions to the coupling constants.