title: Universal dimer in a collisionally opaque medium: experimental observables and Efimov resonances.
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.
authors.affiliation: Department of Physics, Bar-Ilan University, Ramat-Gan, 52900 Israel.
authors.forename: Olga
authors.initials: O
authors.lastname: Machtey
authors.forename: David A
authors.initials: DA
authors.lastname: Kessler
authors.forename: Lev
authors.initials: L
authors.lastname: Khaykovich