1/N: The 1/N expansion was used to show the existence of a spin-flavor symmetry for baryons, and to classify the structure of the 1/N corrections. The predictions are in excellent agreement with data, and have important implications for the properties of baryons (masses, magnetic moments, pion couplings, etc.). The 1/N expansion has been used to explain the successes of the naive quark model and the Skyrme model.
Heavy Quark Effective Theory: Applications of effective theory methods to hadrons containing a heavy quark. Topics include inclusive decays, radiative corrections, and the upsilon expansion.
Chiral Perturbation Theory: Developed a systematic power counting expansion for baryon chiral perturbation theory. See talks by Jenkins and by Manohar at the workshop on Effective Field Theories, Dobogoko, Hungary, 1991.
Non-relativistic Effective Theories: Developed a consistent effective theory formalism for nonrelativistic QED and QCD that uses a renormalization group in velocity space.
PDG: Member of the Particle Data Group, which produces the Review of Particle Physics.