Gluon shadowing and charmonium/bottonium production on nuclear targets

Abstract

We examine the suppression of J/ω, ω' and Ψ production on nuclear targets, as observed for proton and pion beams of energies from 200 to 800 GeV. We find that this suppression leads to a universal scaling curve, which indicates that it is due to nuclear modifications of the gluon density ("shadowing"). A parametrisation of the nuclear effect on the gluon density is extracted from the data and used to obtain quantitative estimates for corresponding effects in high-energy heavyion collisions.