The Relative $J/Ψ$ to $Ψ'$ Suppression in Proton-Nucleus and Nucleus-Nucleus Collisions

Abstract

We calculate the nuclear suppression for $J/Ψ$ and $Ψ'$ production within a coupled channel approach in the subspace of the $J/Ψ$ and $Ψ'$ states. We are able to explain, why (i) the $J/Ψ$ and $Ψ'$ show the same suppression from $200\ GeV$ to $800\ GeV$ in proton-nucleus collisions and why (ii) the $Ψ'$ is absorbed more strongly than the $J/Ψ$ in nucleus-nucleus collisions at $200\ GeV$. The numerical result which includes only interactions with nucleons acconts for half of the observed suppression in sulphur-uranium collisions.