  The prospects of sympathetic cooling of polar molecules with magnetically
co-trapped alkali-metal atoms are generally considered poor due to strongly
anisotropic atom-molecule interactions leading to large spin relaxation rates.
Using rigorous quantum scattering calculations based on ab initio interaction
potentials, we show that inelastic spin relaxation in low-temperature
collisions of CaH(2Sigma) molecules with Li and Mg atoms occurs at a slow rate
despite the strongly anisotropic interactions. This unexpected result, which we
rationalize using multichannel quantum defect theory, opens up the possibility
of sympathetic cooling of polar 2Sigma molecules with alkali-metal and
alkaline-earth atoms in a magnetic trap.
