Photoproduction of of l=1 Baryons: Quark Model versus Large N_c

Abstract

We consider the electromagnetic decays of the orbitally-excited SU(6) 70-plet baryons, to compare the predictions of the naive quark model with those of large-N_c QCD. The helicity amplitudes measured in N^* photoproduction are computed in a large-N_c effective field theory, based on a Hartree approximation, and the amplitudes are fit to the current experimental data. Our results indicate that the success of the naive quark model predictions cannot be explained by large-N_c arguments alone. This is consistent with the conclusions of an earlier study of the N^*\to N\pi decays, that utilized the same approach.

Comments: 17 pages LaTeX, four EPS figures