SEARCHING FOR THE QUARK–DIQUARK SYSTEMATICS OF BARYONS COMPOSED BY LIGHT QUARKS q = u, d

Supposing quark–diquark structure of baryons, we look for systematics of baryons composed of light quarks (q = u,d). We systematize baryons using the notion of two diquarks: (i) axial–vector state, D 1 , with the spin SD = 1 and isospin ID = 1 and (ii) scalar one, D 0 , with the spin SD = 0 and isospin ID = 0. We consider several schemes for the composed baryons: (1) with different diquark masses, M D 0 6 M D 1 , (2) with MD0 = MD1 and overlapping qD 0 0 and qD 1 states (resonances), (3) with/without SU(6) constraints for low-lying states (with quark–diquark orbital momenta L = 0). In the high-mass region the model predicts several baryon resonances at M ∼ 2.0−2.9 GeV. Moreover, the model gives us the double pole structure (i.e. two poles with the same ReM but different ImM) in many amplitudes at masses M > 2.0 GeV. We see also that for description of low-lying baryons (with L = 0), the SU(6) constraint is needed.