SU(3) flavor symmetry breaking in large $N_c$ excited hyperons

Abstract: The $1/N_c$ expansion method for studying the mass spectrum of excited baryons is shortly reviewed together with applications to mixed symmetric states. The $[{\bf 70, \ell^+}]$ multiplet, belonging to the $N$ = 2 band, is reanalyzed, with emphasis on hyperons and the SU(3) symmetry breaking operators entering the mass formula to first order. An important result is that the hierarchy of masses as a function of strangeness is correctly reproduced for all multiplets. Predictions for unknown excited hyperons to SU(6) $\times$ O(3) multiplets are made.