6533b827fe1ef96bd1286f23

RESEARCH PRODUCT

$J/\psi$ reaction mechanisms and suppression in the nuclear medium

subject

description

Recent studies of the interaction of vector mesons with nuclei make possible and opportune the study of the interaction of the $J/\psi$ with nuclei and the investigation of the origin of the $J/\psi$ suppression in its propagation thorough a nuclear medium. We observe that the transition of $J/\psi N$ to $VN$ with $V$ being a light vector, $\rho, \omega,\phi$, together with the inelastic channels, $J/\psi N \to \bar D \Lambda_c$ and $J/\psi N \to \bar D \Sigma_c$ 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 $\pi \Lambda_c$ or $\pi \Sigma_c$. The cross section has a peak around $\sqrt s=4415$ MeV, where the $J/\psi N$ couples to a resonance predicted recently. We study the transparency ratio for electron induced $J/\psi$ production in nuclei at about 10 GeV and find that 30 - 35% of the $J/\psi$ produced in heavy nuclei are absorbed inside the nucleus. This ratio is in line with depletions of $J/\psi$ though matter observed in other reactions.