  Ultracold molecules can be associated from ultracold atoms by ramping the
magnetic field through a Feshbach resonance. A reverse ramp dissociates the
molecules. Under suitable conditions, more than one outgoing partial wave can
be populated. A theoretical model for this process is discussed here in detail.
The model reveals the connection between the dissociation and the theory of
multichannel scattering resonances. In particular, the decay rate, the
branching ratio, and the relative phase between the partial waves can be
predicted from theory or extracted from experiment. The results are applicable
to our recent experiment in 87Rb, which has a d-wave shape resonance.
