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arXiv · 1812.03903

Width and shift of Fano-Feshbach resonances for van der Waals interactions

Pascal Naidon·Ludovic Pricoupenko
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Abstract

We revisit the basic properties of Fano-Feshbach resonances in two-body systems with van der Waals tail interactions, such as ultracold neutral atoms. Using a two-channel model and two different methods, we investigate the relationship between the width and shift of the resonances and their dependence on the low-energy parameters of the system. Unlike what was previously believed [Rev. Mod. Phys. 82, 1225 (2010)] for magnetic resonances, we find that the ratio between the width and the shift of a resonance does not depend only on the background scattering length, but also on a closed-channel scattering length. We obtain different limits corresponding to different cases of optical and magnetic resonances. Although the generalisation of the theory to the multi-channel case remains to be done, we found that our two-channel predictions are verified for a specific resonance of lithium-6.

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Pascal Naidon, Ludovic Pricoupenko. 2019-10-17. Width and shift of Fano-Feshbach resonances for van der Waals interactions. https://doi.org/10.1103/physreva.100.042710

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