Quarkonia results from PHENIX

Abstract

Abstract Measuring the production of multiple quarkonia states in different collision systems and over a range of energies is necessary to disentangle the effects of production in a nuclear target from those due to a hot medium. Measurements by PHENIX of J / ψ production in A + A collisions show similar levels of modification over a range of collision systems as well as energies, which might be explained by an interplay between suppression and regeneration in hot nuclear matter. Measurements of J / ψ and ψ ′ production in d + Au collisions at s NN = 200 GeV have presented a number of interesting puzzles. The p T dependence of J / ψ suppression is found to be different at backward (Au-going) rapidities compared to mid and forward (d-going) rapidities. While this is unexplained by models, comparisons to the modification of heavy flavor muons show a similar discrepancy between backward and forward rapidities. The increased suppression of ψ ′ production compared to J / ψ production in central events is incompatible with either nPDF modification or nuclear breakup. However, an approximate scaling of the relative modification of the ψ ′ to the J / ψ with charged particle multiplicity between SPS p + A , PHENIX d + Au and SPS A + A is also observed, perhaps indicating that interactions with final state partons or hadrons may be important.