Feshbach resonances in ultracold atomic and molecular collisions: threshold behaviour and suppression of poles in scattering lengths
Abstract
Description
In the absence of inelastic scattering, Feshbach resonances produce poles in scattering lengths and very large peaks in elastic cross sections. However, inelastic scattering removes the poles. Whenever the resonant state is coupled comparably to the elastic and inelastic channels, the scattering length exhibits only a small oscillation and peaks in cross sections are dramatically suppressed. A resonant scattering length is defined to characterize the amplitude of the oscillation, and is shown to be small for many collisions of ultracold molecules. The results suggest that cross sections for ultracold molecular inelastic collisions are much less sensitive to details of the potential than has been believed.
10 pages, 2 figures. Version 4 has slightly revised content to reflect the realisation that the resonant scattering length a_res can be complex, which will sometimes produce a reduction in inealastic scattering near a resonance
10 pages, 2 figures. Version 4 has slightly revised content to reflect the realisation that the resonant scattering length a_res can be complex, which will sometimes produce a reduction in inealastic scattering near a resonance