Multiquark Systems in a Constituent Quark Model with Chiral Dynamics
  We discuss the stability of multiquark systems within the recent model of Glozman et al. where the chromomagnetic hyperfine interaction is replaced by pseudoscalar-meson exchange. We find that such an interaction binds a heavy tetraquark system $QQ\bar q\bar q$ ($Q=c, b$ and $q=u, d)$ by $0.2-0.4$ GeV. This is at variance with results of previous models where $cc\bar q\bar q$ is unstable. 
S. Pepin, Fl. Stancu (Liege University), M. Genovese, J.-M. Richard   (Grenoble)