Associated jpsi + gamma diffractive production: the nature of Pomeron and test of hard diffractive factorization

We present a study of diffractive associated jpsi + gamma production at the Fermilab Tevatron and LHC based on the Ingelman-Schlein model for hard diffractive scattering and the factorization formalism of NRQCD for quarkonia production. We find that this process (p + pbar to p + jpsi + gamma + X) can be used to probe the gluon content of the Pomeron and test the assumption of diffractive hard scattering factorization. Using the renormalized Pomeron flux factor D simeq 0.11 (0.052), the single diffractive jpsi + gamma production cross section at 4<P_T< 10 GeV, -1<eta<1 region is found to be of the order of 3.0 pb (8.5 pb), the ratio of single diffractive to inclusive production is 0.50% (0.15%) in central region at the Tevatron (LHC) for the gluon fraction in the Pomeron f_g = 0.7, independent of the values of color-octet matrix elements.