2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/180512We analyze the photo-production helicity amplitudes for the positive parity excited baryons in the context of the $1/N_c$ expansion of QCD. The results show that sub-leading corrections in $1/N_c$ are important and that, while 1-body effective operators are dominant, there is some evidence for the need of 2-body effects.10 pagesHigh Energy Physics - Phenomenologytext