Renormalization Group Limit Cycles in Quantum Mechanical Problems
  We formulate a renormalization group (RG) for the interaction parameters of the general two-body problem and show how a limit cycle emerges in the RG flow if the interaction approaches an inverse square law. This limit cycle generates a scaling structure in the energy spectrum. Our demonstration is relevant to the Efimov problem in nuclear physics where similar scaling appears. 
Erich J. Mueller (Cornell) and Tin-Lun Ho (Ohio State)