Excited L=1 baryons in large Nc QCD

Abstract

The physics of the orbitally excited baryons simplifies drastically in the large Nc limit. The states are arranged into irreducible representations of the contracted SU(4)_c symmetry, with mixing angles determined exactly. The ratios of the strong couplings N* -> [N\pi]_{S,D} are predicted in this limit, with results in agreement with those following from the quark model (with the large Nc mixing angles). We present a phenomenological analysis of the observed nonstrange baryons from the perspective of the 1/Nc expansion, including constraints from their masses and strong decays.