Looking for the gluonic EMC effect in associated $J/\psi$ + $\gamma $   production
  We study the associated production of $ J/\psi\ + \gamma $ in fixed-target experiments with nuclear targets as well as at the relativistic heavy-ion collider (RHIC). We find that this process affords a very clean probe of $\rho_g$, the ratio of gluon density in a heavy nucleus to that of a proton. The combined $x$ range thus available can be used to discriminate between the predictions of different models of the EMC effect for $\rho_g$. 
R.V. Gavai, R.M. Godbole and K. Sridhar