Quantum defect theory for high-partial-wave cold collisions

We introduce a choice of reference wave functions that allows multichannel quantum defect theory (MQDT) to describe ultracold collisions involving high-partial-wave quantum numbers L. This requires a careful standardization of the MQDT reference wave functions at long range to ensure their linear independence. To illustrate the simplicity and accuracy of the resulting theory, we perform a comprehensive calculation of L <= 2 Fano-Feshbach resonances in the range 0-1000 G for the scattering of K-40 + Rb-87 in their lowest hyperfine states. Moreover, we derive analytic expressions for our universal set of MQDT parameters in the threshold regime. DOI: 10.1103/PhysRevA.87.032706