An asymptotic bound state model to predict Feshbach resonances

eshbach resonances play a central role in the manipulation of the interparticle interaction in ultracold atomic gases. The Asymptotic Bound-state Model (ABM) [1,2] is a powerful and easy-to-use tool to predict properties of these Feshbach resonances. This model exploits the fact that only the least bound states in the interaction potential determine the low energy interaction properties. These bound states are coupled by hyperfine and Zeeman interactions, and the intersection of these coupled bound states with the scattering threshold determine the position of these Feshbach resonances. The high accuracy of this model was clearly demonstrated when assigning 13 resonances in the 6Li-40K mixture by using only two bound state parameters [1]. Here we discuss the extension of the ABM by the including threshold effects, which allow for the prediction of the resonance width as well.