Alternate 1/N _c expansions and SU(3) breaking from baryon lattice results

A combined expansion in the number of QCD colors 1/N _c and SU(3) flavor-breaking parameter μ has long been known to provide an excellent accounting for the mass spectrum of the lightest spin-12, 32 baryons when the quarks are taken to transform under the fundamental SU(N _c) representation, and in the final step N _c→3 and μ is set to its physical value ∼0.3. Subsequent work shows that placing quarks in the two-index antisymmetric SU(N _c) representation leads to quantitatively equally successful mass relations. Recent lattice simulations allow for varying the value of μ and confirm the robustness of the original 1/N _c relations. In this paper we show that the same conclusion holds for the antisymmetric quarks and demonstrate that the mass relations also hold under alternate prescriptions for identifying physical baryons with particular members of the large N _c multiplets.