Heavy quarkonium production in double pomeron exchange processes in perturbative QCD

We calculate the heavy quarkonium production in double pomeron exchange processes in perturbative QCD by using two-gluon exchange model. For the P-wave χ_J productions, we find χ₁ and χ₂ production amplitudes which vanish in the forward scattering limit. We also calculate direct J/ψ()+γ production in the same approach, and these direct contributions are much smaller than the feeddown contributions from the P-wave states.