Excited baryon decay widths in largeNcQCD

Abstract

We study excited baryon decay widths in large ${N}_{c}$ QCD. It was suggested previously that some spin-flavor mixed-symmetric baryon states have strong couplings of ${O(N}_{c}^{\ensuremath{-}1/2})$ to nucleons [implying narrow widths of ${O(1/N}_{c})],$ as opposed to the generic expectation based on Witten's counting rules of an ${O(N}_{c}^{0})$ coupling. The calculation obtaining these narrow widths was performed in the context of a simple quark-shell model. This paper addresses the question of whether the existence of such narrow states is a general property of large ${N}_{c}$ QCD. We show that a general large ${N}_{c}$ QCD analysis does not predict such narrow states; rather they are a consequence of the extreme simplicity of the quark model.