Quantum mechanical coupled channel scattering calculations are performed for the ro-
vibrational relaxation of CO in collisions with ultracold He atoms. The van der Waals well in
the interaction potential supports a number of shape resonances which significantly
influence the relaxation cross sections at energies less than the well depth. Feshbach
resonances are also found to occur near channel thresholds corresponding to the j= 1
rotational level in the v= 0 and v= 1 vibrational levels. Their existence influences …