Universal Dimer in a Collisionally Opaque Medium: Experimental   Observables and Efimov Resonances
  A universal dimer is subject to secondary collisions with atoms when formed in a cloud of ultracold atoms via three-body recombination. We show that in a collisionally opaque medium, the value of the scattering length that results in the maximum number of secondary collisions may not correspond to the Efimov resonance at the atom-dimer threshold and thus can not be automatically associated with it. This result explains a number of controversies in recent experimental results on universal three-body states and supports the emerging evidence for the significant finite range corrections to the first excited Efimov energy level. 
Olga Machtey, David A. Kessler and Lev Khaykovich
cond-mat.quant-gas physics.atom-ph quant-ph