Closed-channel parameters of Feshbach resonances

• URL: http://arxiv.org/abs/2403.14962v3
• Date: Mon, 21 Oct 2024 02:37:54 GMT
• Title: Closed-channel parameters of Feshbach resonances
• Authors: Pascal Naidon,
• Abstract summary: The two-body observables associated with a Feshbach resonance can be insensitive to the properties of the closed channel. This is the case for all magnetic Feshbach resonances in ultracold atoms.
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• Abstract: This work investigates how the closed channel of a Feshbach resonance is characterised by experimental observables. Surprisingly, it is found that the two-body observables associated with the Feshbach resonance can be insensitive to the properties of the closed channel. In particular, it is impossible in this situation to determine the energy of the bound state causing the resonance from the usual experimental data. This is the case for all magnetic Feshbach resonances in ultracold atoms, due to their deep two-body interaction potentials. This insensitivity highlights a major difference with Feshbach resonances that involve shallow interaction potentials, such as hadron resonances. It appears however that short-range two-body correlations and three-body observables are affected by a parameter of the closed channel called the "closed-channel scattering length". A photoassociation experiment is proposed to measure this parameter in ultracold atom systems.

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