Spin relaxation in ultracold collisions of molecular radicals with alkali-metal atoms

We present accurate quantum scattering calculations of spin relaxation in ultracold collisions of alkali-metal atoms and polar $^2\Sigma$ molecules CaH, SrF, and SrOH. The calculations employ state-of-the-art ab initio interaction potentials and a rigorous quantum theory of atom-molecule collisions in a magnetic field based on the total angular momentum representation. We will further discuss the relevance of the results to atom-molecule sympathetic cooling experiments in a magnetic trap.