Preface: MENU-2019, the 15th International Conference on Meson-Nucleon Physics and the Structure of the Nucleon
In the first part I briefly survey recent issues in constituent quark models raised by the observation of unusual hadronic states. In particular I discuss the role of higher Fock components in the wave function of baryons and the possible interpretation of open charm and of new charmonium-type resonances as tetraquarks. In the second part I show support for the quark model dynamics obtained in a model independent way from the 1/Nc expansion approach of QCD which proved to be successful in describing baryon properties.
On the existence of heavy tetraquarks
Previous work done in collaboration with David Brink is reviewed in the light of the recent observation of new charmonium-like resonances which can be interpreted as tetraquarks. In the framework of a schematic quark model the spectrum of ccqq tetraquarks is presented. 1 e-mail: fstancu@ulg.ac.be
The Tcc = DD* Molecular State
Abstract.We show that the molecule-like configuration of DD* enables weak binding with two realistic potential models (Bhaduri and Grenoble AL1). Three-body forces may increase the binding and strengthen the cc diquark configuration. As a signature we propose the branching ratio between radiative and pionic decay.