The universal Ψ′/Ψ′ ratio as unambiguous signature for hard physics in nuclear reactions and in decays of beauty hadrons

We suggest the ratio of the Ψ″(3770)/Ψ′(3686) production cross sections as an unambiguous probe of the dominance of hard, point-like physics in charmonium production. If hard physics dominates the charmonium production the ratio: σ(Ψ″)/σ(Ψ′) ≈ Γ(Ψ″→1⁺1^-)/Γ(Ψ ′→1⁺1^-) ≈ 0.1 is independent of the process. We argue that since the dominant DD̄ decay mode of the Ψ″-meson can be detected with a high efficiency at the current facilities the effective counting rate for the Ψ″ production should be comparable to that of the Ψ′ and hence it could be observed at the B-factories. Even in hadron induced processes the ratio will not be changed significantly by final state interactions due to the similar mass and size of these two charmonium states. A possible exception are the charmonium state interactions with low energy particles - comovers - which are especially relevant for heavy ion collisions.