Excited baryons in large [Formula Presented] QCD reexamined: The resonance picture versus single-quark excitations

We analyze excited baryon properties via a [Formula Presented] expansion from two perspectives: as resonances in meson-nucleon scattering, and as single-quark excitations in the context of a simple quark model. For both types of analysis one can derive novel patterns of degeneracy that emerge as [Formula Presented] and that are shown to be compatible with one another. This helps justify the single-quark excitation picture and may give some insight into its successes. We also find that in the large [Formula Presented] limit one of the [Formula Presented] baryons does not couple to the [Formula Presented] channel but couples to the [Formula Presented] channel. This is empirically observed in the [Formula Presented] which couples very weakly to the [Formula Presented] channel and quite strongly to the [Formula Presented] channel. The comparatively strong coupling of the [Formula Presented] to the [Formula Presented] channel and weak coupling to [Formula Presented] channel is also predicted. In the context of the simple quark model picture we reproduce expressions for mixing angles that are accurate up to [Formula Presented] corrections and are in good agreement with mixing angles extracted phenomenologically.