Analysis of 56-plet positive parity baryon decays in the 1 / N c expansion

Abstract

The partial decay widths of positive parity baryons belonging to 56-plets of SU(6) are analyzed in the framework of the 1/Nc expansion. The channels considered are those with emission of a single pi, K, or barK meson, and the analysis is carried out to subleading order in 1/Nc and to first order in SU(3) symmetry breaking. The results for the multiplet [56,0+], to which the Roper resonance belongs, indicate a poor description of the widths at leading order, requiring important next to leading order corrections. For the multiplet [56,2+], the P wave decays in the nonstrange sector are well described at leading order, while the F wave decays require the next to leading order corrections, which turn out to be of natural magnitude. SU(3) breaking effects are poorly determined, because only few decays with a K meson in the final state are established, and their widths are not known with sufficient accuracy.