RelativeJ/ψtoψ′Suppression in Proton-Nucleus and Nucleus-Nucleus Collisions

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