We consider a novel mechanism for $J/\psi$ production in nuclear collisions arising due to the high density of gluons. The resulting $J/\psi$ production cross section is evaluated as a function of rapidity and centrality. We compute the nuclear modification factor and show that the rapidity distribution of the produced $J/\psi$’s is significantly more narrow in $AA$ collisions due to the gluon saturation effects. Our results indicate that gluon saturation in the colliding nuclei is a significant source of $J/\psi$ suppression and can explain the experimentally observed rapidity and centrality dependencies of the effect.

• Received 22 August 2008

DOI:https://doi.org/10.1103/PhysRevLett.102.152301