$J/ψ$ reaction mechanisms and suppression in the nuclear medium

Recent studies of the interaction of vector mesons with nuclei make possible and opportune the study of the interaction of the $J/ψ$ with nuclei and the investigation of the origin of the $J/ψ$ suppression in its propagation thorough a nuclear medium. We observe that the transition of $J/ψN$ to $VN$ with $V$ being a light vector, $ρ, ω,ϕ$, together with the inelastic channels, $J/ψN \to \bar D Λ_c$ and $J/ψN \to \bar D Σ_c$ leads to a particular shape of the inelastic cross section. Analogously, we consider the mechanisms where the exchanged $D$ collides with a nucleon and gives $πΛ_c$ or $πΣ_c$. The cross section has a peak around $\sqrt s=4415$ MeV, where the $J/ψN$ couples to a resonance predicted recently. We study the transparency ratio for electron induced $J/ψ$ production in nuclei at about 10 GeV and find that 30 - 35% of the $J/ψ$ produced in heavy nuclei are absorbed inside the nucleus. This ratio is in line with depletions of $J/ψ$ though matter observed in other reactions.

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