Universal physics with ultra cold atoms

When two particles are attracted by a resonant, short-range interaction, three partic;es lways form an infinite tower of bound states characterized by a discrete scaling symmetry. This phenomenon is known as the Efimov effect. Keywords regarding the Efimov effect are universality, scale invariance, quantum anomaly, and renormalization group limit cycle. I will give a pedagogical talk on how these keywords appear in its understanding and discuss its observation in ultracold atom experiments. If time permits, I will introduce my recent work in which such few-body physics plays an important role in probing many-body physics of strongly-interacting atomic gases.