We present a study of diffractive associated $J/\psi +\gamma$ production at energies reached at the Fermilab Tevatron and CERN LHC based on the Ingelman-Schlein model for hard diffractive scattering and the factorization formalism of nonrelativistic QCD for quarkonia production. We find that this process $(p+\overline{p}\to p+J/\psi +\gamma +X)$ 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 $D\simeq 0.11\left(0.052\right)\mathrm{}$ at Tevatron (LHC) energy, the single diffractive associated $J/\psi +\gamma$ production cross section in the region of $4<\mathrm{}{P}_T<10\mathrm{}\mathrm{GeV},$ $-1<\mathrm{}\eta <1\mathrm{}$ 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 the central region at the Tevatron (LHC) for the gluon fraction in the Pomeron $f_g=0.7,$ independent of the values of the color-octet matrix elements.

• Received 2 July 1998

DOI:https://doi.org/10.1103/PhysRevD.59.014028