Nuclear effects on J/ψ production in proton–nucleus collisions

Abstract

The study of nuclear effects for J/ψ production in proton–nucleus collisions is crucial for a correct interpretation of the J/ψ suppression patterns experimentally observed in heavy-ion collisions. By means of three representative sets of nuclear parton distribution, the energy loss effect in the initial state and the nuclear absorption effect in the final state are taken into account in the uniform framework of the Glauber model. A leading order phenomenological analysis is performed on J/ψ production cross-section ratios R_W/Be(x_F) for the E866 experimental data. The J/ψ suppression is investigated quantitatively due to the different nuclear effects. It is shown that the energy loss effect with resulting in the suppression on R_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 large anti-shadowing effect. However, the new HERA-B measurement is not in support of the anti-shadowing effect in the nuclear gluon distribution. It is found that the J/ψ–nucleon inelastic cross section \(\sigma^{J/\psi}_{\mathrm{abs}}\) depends on the kinematical variable x_F, and increases as x_F in the region x_F>0.2.