Exotic hadrons as Feshbach resonances

Since ten years ago a host of exotic resonances have challenged the usual quarkonium picture. A number of ideas have been put forward to explain these new states, but a comprehensive framework is still missing. We review the estimates for prompt production cross sections at hadron collider, and show that the interpretation of exotic states in terms of hadron molecules is not favored. We show a recently proposed model to solve this paradox and to explain the nature of above-threshold states in terms of Feshbach resonances.