Ultracold lithium few-body puzzles

A ubiquitous property of ultracold gases is the tunability of two-body interactions. When these interactions are resonantly enhanced, the quantum mechanical scattering problem supports weakly bound three-body states with universal properties. The latter means independence of details of the short-range interaction potentials and a discrete scaling invariance. Various aspects of this universality have been successfully demonstrated theoretically and experimentally in several atomic species in a recent decade. Lithium, however, remains a notable exception stubbornly refusing to concur with the emergent framework. In this talk I shall overview the subject and describe an increasingly involved theory-experiment collaborative effort to reveal the physics responsible for this puzzling behavior.