Ground state baryons in the unitarised quark model

Abstract

Hadronic self-energy effects for the ground state baryons (B) are discussed within the framework of the unitarised quark model. The contributions from all pseudoscalar (P) and vector (V) mesons in the self-energyB→P B′→B, B→V B′→B loops are taken into account. It is assumed that all mass splittings (barring the strange “quark mass” difference) are due to the unitarity effects only. Under this assumption a good description of the mass pattern of the ground state baryons is achieved with only a weak (and consistent with experiment) deviation fromSU(6) W symmetry for hadronic vertices. In particular it is thus shown that the unitarity effects—which contribute with the same sign as the conventional one-gluon exchange mechanism to Δ−N and Σ−Λ splitting—can alone explain both the Δ−N and Σ−Λ mass differences.