Lawrence Berkeley National Laboratory

We formulate the single transverse spin asymmetry in heavy quarkoniumproduction in lepton-nucleon and nucleon-nucleon collisionsin the non-relativistic limit. We findthat the asymmetry is very sensitive to the production mechanism. The finalstate interactions with the heavy quark and antiquark cancel out among themselves whenthe pair are produced in a color-single configuration, or cancel out with the initialstate interaction in pp scattering when they are in color-octet. As a consequence, the asymmetry is nonzero in ep collisions only in the color-octet model, whereas in pp collisions only in the color-singlet model.