Multiquark hadrons

Abstract

A new extended model (the MIT bag model) that implies many present understandings of hadron dynamics is reviewed. In the model the light hadron (Q$\overline{Q}$ mesons & QQQ baryons) structure is discussed and their mass spectra are given. Next the spectra and dominant decay couplings of S-wave $Q^2\overline{Q}^2$ mesons and the techniques for estimating them are presented. The dynamics is based on a quark-bag model of light, colored, and permanently confined quarks gauge-coupled to non-abelian colored gluons. Certain known $O^+$ mesons (ε, $S^*$, δ, K) are assigned to the lightest crypto-exotic S-wave $Q^2\overline{Q}^2$ nonet. Finally $Q^2\overline{Q}^2$ mesons which couple strongly to the B$\overline{B}$ channel are classified. The quantum numbers and masses of prominent states are predicted from the MIT-bag model. The couplings of $Q^2\overline{Q}^2$ states to BB are estimated using 3Po model and peripherality. Important $Q^2\overline{Q}^2$ resonances in the elastic N$\overline{N}$ scattering and the N$\overline{N} → $\pi\pi$ process are enumerated. Baryoniums T(2.15), U(2.31), and V(2.48) are assigned to $Q^2\overline{Q}^2$ states with high angular momenta.