Searching for QGP: the J/ψ probe in the NA50/CERN experiment

The $\mathrm{J/\psi }$ production in 158 A GeV Pb-Pb interactions is studied as a function of centrality. Its pattern, after a first sharp variation around ${\mathrm{E}}_{\mathrm{T}}\text{=40\hspace{0.05em}}\mathrm{GeV},$ continues to fall down and exhibits a curvature change around ${\mathrm{E}}_{\mathrm{T}}\text{=90\hspace{0.05em}}\mathrm{GeV}.$ This trend excludes any conventional hadronic model and is in agreement with a deconfined quark-gluon phase scenario.