On the Origin of the $XYZ$ Mesons
  In this talk we present a mechanism giving rise to exotic $XYZ$ four-quark states in the meson spectra within a constituent quark model approach. We discuss its generalization to five-quark states in the heavy baryon sector. Finally, we revise some other works in the literature and experimental data where this mechanism may be working. 
A. Valcarce, J. Vijande
hep-ph nucl-th