Evidence for a spin-quartet of nucleon resonances at 2\,GeV

Abstract

Results from a multi-channel partial wave analysis of elastic and inelastic $\pi N$ and $\gamma N$ induced reactions are presented. The analysis evidences the existence of a spin-quartet of nucleon resonances with total angular momenta $J^P=1/2^+,..., 7/2^+$. All states fall into a $\pm130$\,MeV mass gap centered at 1.97\,GeV. The spin quartet is at variance with S-wave diquark configurations required in classical di-quark models.