Search

We analyze the photoproduction helicity amplitudes for positive-parity excited baryons in the context of the 1/N(c) expansion of QCD. The results show that subleading corrections in 1/N(c) are important and that, while one-body effective operators are dominant, there is some evidence for the need for two-body effects.

The masses of the negative parity 70-plet baryons are analyzed in large N(c) QCD to order 1/N(c) and to first order in SU(3) symmetry breaking. The existing experimental data are well reproduced and 20 new observables are predicted. The leading order SU(6) spin-flavor symmetry breaking is small and, as it occurs in the quark model, the subleading in 1/N(c) hyperfine interaction is the dominant source of the breaking. It is found that the Lambda(1405) and Lambda(1520) are well described as three-quark states and spin-orbit partners. New relations between splittings in different SU(3) multiplets are found.