Origin of the Universal Three-body Parameter in Atomic Efimov Physic

Pascal Naidon, Shimpei Endo, Masahito Ueda

J. P. D’Incao, J. Wang, Brett D. Esry +1 more

Peder K. Sørensen, D. V. Fedorov, A. S. Jensen +1 more

We calculate shallow three-body bound states in the universal regime, defined by Efimov, with inclusion of both scattering length and effective range parameters. We find corrections to the universal scaling laws for large binding energies. For narrow resonances we find a distinct nonmonotonic behavior of the threshold at which the lowest Efimov trimer merges with the three-body continuum. The origin of the three-body parameter is related to the two-body atom-atom interactions in a physically clear model. Our results demonstrate that experimental information from narrow Feshbach resonances and/or mixed systems are of vital importance to pin down the relation of two- and three-body physics in atomic systems.

Yusuke Nishida, 仁子 関口, K. Sekiguchi +2 more

Pascal Naidon, Shimpei Endo, Masahito Ueda

We address the microscopic origin of the universal three-body parameter that fixes the spectrum of three-atom systems in the Efimov regime. We identify it with the van der Waals two-body correlation, which causes the three-atom system to deform when the three atoms come within the distance of the van der Waals length, effectively preventing them from coming closer due to the kinetic-energy cost associated with three-body deformation. This deformation mechanism explains the universal ratio of the scattering length at the triatomic resonance to the van der Waals length observed in several experiments and confirmed by numerical calculations.

J. von Stecher, José Paulo D'Incao, Chris H. Greene