j_psi Suppression and the Quark-Gluon Plasma

Abstract

All measured Feynman x_f distributions of the ratio, R, of j_psi production in nuclei relative to production on protons fall off with x_f. They show [2] that absorption of charmonium cannot be the only source of j_psi suppression and that energy loss of the constituents of the incident proton prior to the j_psi production, because of the exponential sqrt(s) dependence of the charmonium cross section, should not be neglected. Including the effects of initial state energy loss we find that the latest measured Pb-Pb j_psi cross sections do not provide any evidence for deconfinement.

Comments: 9 pages, 2 figures, additional material, accepted by Physics Letters