Quarkonium production through hard comover rescattering in polarized and unpolarized pp scattering

In this paper hadroproduction of charmonium states in polarized pp collisio ns is discussed. A thermal picture for the gluonic cloud of comovers is giv en making contact between the formalism and the measured unpolarized cross sections. The experimentally observed non-polarization of the final J/psi s tates leads to the consequence that no correlations between the initial pro ton spin and the final charmonium spin should be existent. Hence the single spin asymmetries vanish to leading order in that model. (C) 2001 Elsevier Science B.V. All rights reserved.