Heavy quarkonium production in double Pomeron exchange processes in perturbative QCD

Abstract

We calculate the heavy quarkonium production in double pomeron exchange processes in perturbative QCD by using two-gluon exchange model. For the $P$-wave ${\chi }_J$ productions, we find ${\chi }_1$ and ${\chi }_2$ production amplitudes which vanish in the forward scattering limit. We also calculate direct $J/\psi ({\rm Y})+\gamma$ production in the same approach, and these direct contributions are much smaller than the feeddown contributions from the $P$-wave states.

Comments: Some discussions and references added