Description
The discovery of a plethora of new resonances, the so-called XYZ states, is challenging the paradigm of the quark model in which mesons and baryons are classified according to the valence quark-antiquark and three-quark configurations, respectively. The new era of particle accelerators has the potential to confirm the observations in previous experiments and to provide complementary insights. Besides, the future Electron-Ion Collider at Brookhaven will reveal the arrangement of the quarks and gluons that make up the protons and neutrons of nuclei, producing snapshots of those particles' internal structure -- like a CT scanner for atoms. In support of the experimental effort, theorists should also play a leading role in counterpart. The ultimate goal of high-energy nuclear theory is to describe the properties of conventional and exotic hadrons from first principles. Since this task is quite challenging, mostly due to QCD's nonperturbative character at low energy, a more modest goal to start with is the development of well-motivated phenomenological tools that specify the colored constituents, how they are clustered and the forces between them.