Universal dimer in a collisionally opaque medium: experimental observables and Efimov resonances

Phys Rev Lett. 2012 Mar 30;108(13):130403. doi: 10.1103/PhysRevLett.108.130403. Epub 2012 Mar 30.

Abstract

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 cannot 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.