Experimental patterns in LHC quarkonium production from pp to AA

Pietro Faccioli


Mid-rapidity LHC measurements of quarkonium production show unexpectedly simple scaling patterns: 1) the J/ψ, ψ(2S), χc1, χc2 and ϒ(nS) pT-differential cross sections are compatible with one universal shape function, an observation complementing the observed lack of polarization in all measured cases; 2) cross-section normalizations and binding energies of the S-wave quarkonia show a remarkable correlation, identical for 7 and 13 TeV data. These results provide a strong experimental evidence supporting the validity of the factorization ansatz, a cornerstone of non-relativistic QCD, still lacking theoretical demonstration. Moreover, they are crucial information for quantitative interpretations of quarkonium production data, including studies of the suppression patterns measured in nucleus-nucleus collisions.