$\Lambda$ and $\Sigma$ Excitations and the Quark Model

Abstract

The spectrum of $\Lambda$ and $\Sigma$ excitations is reviewed taking into account (nearly) all hyperon resonances which were seen in early analyses or in one of the recent partial-wave analyses. The spectrum is compared with the old Isgur-Karl model and the Bonn model. These models allows us to discuss the SU(3) structure of the observed resonances. The SU(3) decomposition is compared with SU(6) relations between the different decay modes. Seven $\Lambda$ states are proposed to be classified as SU(3) singlet states. The hyperon spectrum is compared with the spectrum of $N$ and $\Delta$ resonances.