Efimov states near a Feshbach resonance and the limits of van der Waals universality at finite background scattering length

Abstract

We calculate the spectrum of three-body Efimov bound states near a Feshbach resonance within a model which accounts both for the finite range of interactions and the presence of background scattering. The latter may be due to direct interactions in an open channel or a second overlapping Feshbach resonance. It is found that background scattering gives rise to substantial changes in the trimer spectrum as a function of the detuning away from a Feshbach resonance, in particular in the regime where the background channel supports Efimov states on its own. Compared to the situation with negligible background scattering, the regime where van der Waals universality applies is shifted to larger values of the resonance strength if the background scattering length is positive. For negative background scattering lengths, in turn, van der Waals universality extends to even small values of the resonance strength parameter, consistent with experimental results on Efimov states in ${}^{39}$K. Within a simple model, we show that short-range three-body forces do not affect van der Waals universality significantly. Repulsive three-body forces may, however, explain the observed variation between around $-8$ and $-10$ of the ratio between the scattering length where the first Efimov trimer appears and the van der Waals length.

17 pages, 13 figures; final version as published

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Cited by in corpus (18)

• Precision Test of the Limits to Universality in Few-Body Physics
• Observation of Efimov Universality across a Non-Universal Feshbach Resonance in \textsuperscript{39}K
• Pinpointing Feshbach Resonances and Testing Efimov Universalities in ${}^{39}$K
• Suppression of Unitary Three-body Loss in a Degenerate Bose-Fermi Mixture
• Finite-range effects in Efimov physics beyond the separable approximation
• Quantum unbinding near a zero temperature liquid-gas transition
• Multichannel effects in the Efimov regime from broad to narrow Feshbach resonances
• Reshaped Three-Body Interactions and the Observation of an Efimov State in the Continuum
• A coherent superposition of Feshbach dimers and Efimov trimers
• Efimov scenario for overlapping narrow Feshbach resonances
• Efimovian three-body potential from broad to narrow Feshbach resonances
• Emergent inflation of the Efimov spectrum under three-body spin-exchange interactions
• Universal Three-Body Parameter of Heavy-Heavy-Light systems with negative intraspecies scattering length
• Temperature dependence of an Efimov resonance in ${}^{39}\mathrm{K}$
• Self-stabilized Bose polarons
• Universality in Ionic Three-body Systems Near an Ion-atom Feshbach Resonance
• Efimov energy level rebounding off the atom-dimer continuum
• Accurate simulation of Efimov physics in ultracold atomic gases with realistic three-body multichannel interactions