Efimovian three-body potential from broad to narrow Feshbach resonances

• Published in: arXiv.org 2023-09
• Main Authors: van de Kraats, J, Ahmed-Braun, D J M, J -L Li, S J J M F Kokkelmans
• Format: Article
• Language: English
• Subjects: Spin structure; Wave functions
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2210.14200

We analyse the change in the hyperradial Efimovian three-body potential as the two-body interaction is tuned from the broad to narrow Feshbach resonance regime. Here, it is known from both theory and experiment that the three-body dissociation scattering length \(a_-\) shifts away from the universal value of \(-9.7 \ r_{\mathrm{vdW}}\), with \(r_{\mathrm{vdW}} = \frac{1}{2} \left(m C_6/\hbar^2 \right)^{1/4}\) the two-body van der Waals range. We model the three-body system using a separable two-body interaction that takes into account the full zero-energy behaviour of the multichannel wave function. We find that the short-range repulsive barrier in the three-body potential characteristic for single-channel models remains universal for narrow resonances, whilst the change in the three-body parameter originates from a strong decrease in the potential depth. From an analysis of the underlying spin structure we further attribute this behavior to the dominance of the two-body interaction in the resonant channel compared to other background interactions.