Multichannel quantum-defect theory for ultracold atom–ion collisions

摘要: We develop an analytical model for ultracold atom?ion collisions using the multichannel quantum-defect formalism. The is based on solutions of r?4 long-range potential and application a frame transformation between asymptotic molecular bases. This approach allows description interaction in domain terms only three parameters: singlet triplet scattering lengths, assumed to be independent relative motion angular momentum, lead dispersion coefficient potential. also introduce corrections lengths that improve accuracy our higher-order partial waves, particularly important result accurate shape Feshbach resonances at finite temperature. theory applied system composed 40Ca+ ion Na atom, compared with numerical coupled-channel calculations carried out ab initio potentials. For this particular system, we investigate spectrum bound states, rate charge-transfer processes collision rates presence magnetic zero