$J/Ψ$ and $Ψ'$ Suppression in Heavy Ion Collisions

We study the combined effect of nuclear absorption and final state interaction with co-moving hadrons on the $J/\Psi$ and $\Psi '$ suppression in proton-nucleus and nucleus-nucleus collisions. We show that reasonable description of the experimental data can be achieved with theoretically meaningful values of the cross-sections involved and without introducing any dicontinuity in the $J/\Psi$ or $\Psi '$ survival probabilities.