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RESEARCH PRODUCT

J/\psi depletion in a nuclear medium

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In this talk, we have taken into account the main decay channel of J/ψ when travelling inside a nucleus. In analogy to all vector mesons in SU(3), where the main decay channel is to two pseudoscalars, in the case of the J/ψ the meson meson channel to which it couples strongly is DD. Taking this into account we study the J/ψN → DΛc and J/ψN → DΣc mediated by D-exchange. To obtain the couplings we use an extension to SU(4) of the local hidden gauge Lagrangians as done in [1]. Analogously, we consider the mechanisms where the exchanged D collides with a nucleon and gives πΛc or πΣc. The sum of these channels produces a J/ψN inelastic cross section which is larger than the elastic one and is responsible for the depletion of J/ψN when propagating through nuclear matter. The cross section has its peak around √ s= 4415 MeV, where the virtual D and one N give rise to the Λc(2595) resonance. We have studied the transparency ratio for photon induced J/ψ production in nuclei at 10 GeV and find that about 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 through matter observed in other reactions.