High precision J/ψ and γ-production data and the nuclear glue

Abstract

We use the high statistics E772 data on the nuclear dependence of the production of quarkonia (J/ψ and γ) and dimuons at large transverse momentum (pT)| in p-A collisions to get information about the gluonic EMC effect. We find a satisfactory quantitative agreement of the theoretical predictions with the data, although none of the models of the EMC effect we consider could account for the entire data. Nonetheless, our results suggest that these data can now be used for a better determination of the nuclear parton densities. Our conclusions are shown to be insensitive to the hadronization mechanism for the quarkonia.