2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/39536We present a model-independent analysis of the mass spectrum of nonstrange L=1 baryons in large N_c QCD. The 1/N_c expansion is used to select and order a basis of effective operators that spans the nine observables (seven masses and two mixing angles). Comparison to the data provides support for the validity of the 1/N_c expansion, but also reveals that only a few nontrivial operators are strongly preferred. We show that our results have a consistent interpretation in a constituent quark model with pseudoscalar meson exchange interactions.5 pages LaTeX. Invited plenary talk, NSTAR2000, Newport News, VA, Feb. 16-19, 2000High Energy Physics - Phenomenologytext