Operator analysis ofl=1baryon masses in largeNcQCD

We consider in detail the mass operator analysis for the nonstrange $l=1\mathrm{}$ excited baryons in large $N_c$ QCD. We present a straightforward procedure for constructing the large $N_c$ baryon wave functions, and provide complete analytic expressions for the matrix elements of all the independent isosinglet mass operators. We discuss the relationship between the old-fashioned operator analyses based on nonrelativistic SU(6) symmetry and the modern large $N_c$ approach, which has a firmer theoretical foundation. We then suggest a possible dynamical interpretation for the subset of operators preferred strongly by the data.