Nuclear Effects On J/Ψ Production In Proton-Nucleus Collisions

J/ψsuppression is considered as a most reliable signature for the formation of Quark Gluon Plasma (QGP) in heavy ion collisions during the present time. Therefore, the production of J/ψin high energy collisions has attracted the extensive attention from both the nuclear and particle physics communities. However, there are many different nuclear effects in nucleus-nucleus collisions. In order to interprete robustly of the experimental data in heavy ion collisions and acquire the signature for the formation of Quark Gluon Plasma, we should investigate the nuclear effects in p-A collisions and understand deeply and quantitatively the basic mechanisms responsible for suppression of J/ψproduction due to the nuclear effects.By means of Color Evaporate Model and three representative sets of nuclear parton distributions, the energy loss effect in initial state and nuclear absorption effect in final state are taken into account in the uniform framework of the Glauber model. A leading ordercalculation is performed on J/ψproduction cross section ratios R_W/Be(x_F) for the E866experimental data. The J/ψsuppression is investigated quantitatively due to the different nuclear effects. It is shown that the energy loss effect with resulting in the suppression onR_W/Be(x_F) is more important than the nuclear effects on parton distributions in high x_F region. The E866 data in the small x_F keep out the nuclear gluon distribution with a largeanti-shadowing effect. However, the new HERA-B measurement is not in support of the anti-shadowing effect in nuclear gluon distribution. It is found that the J/ψ-nucleon inelasticcross section (?) depends on the kinematical variable x_F, and increases as x_F.