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Feshbach resonances with large background scattering length: Interplay with open-channel resonances

2004; American Physical Society; Volume: 70; Issue: 1 Linguagem: Inglês

10.1103/physreva.70.012701

1538-4446

Bout Marcelis, E. van Kempen, B. Verhaar, S. J. J. M. F. Kokkelmans,

Atomic and Subatomic Physics Research

Feshbach resonances are commonly described by a single-resonance Feshbach model, and open-channel resonances are not taken into account explicitly. However, an open-channel resonance near threshold limits the range of validity of this model. Such a situation exists when the background scattering length is much larger than the range of the interatomic potential. The open-channel resonance introduces strong threshold effects not included in the single-resonance description. We derive an easy-to-use analytical model that takes into account both the Feshbach resonance and the open-channel resonance. We apply our model to $^{85}\mathrm{Rb}$, which has a large background scattering length, and show that the agreement with coupled-channel calculations is excellent. The model can be readily applied to other atomic systems with a large background scattering length, such as $^{6}\mathrm{Li}$ and $^{133}\mathrm{Cs}$. Our approach provides full insight into the underlying physics of the interplay between open-channel (or potential) resonances and Feshbach resonances.