Double spin asymmetries in P-wave charmonium hadroproduction

We discuss the double spin asymmetries in P-wave charmonium hadroproduction with non-zero transverse momenta at fixed target energies, s≃40 GeV, within the framework of the factorization approach. The size of the asymmetries and the projected statistical errors in a future option of HERA with longitudinally polarized protons scattering off a polarized target (HERA-N) are calculated. Measurements of the χc1 and χc2 decays into dilepton plus photon should allow to distinguish between different parametrizations for the polarized gluon distribution in the proton. At higher energies (s=200 GeV) the situation appears less favourable with the presently envisaged integrated luminosities of the polarized RHIC collider.