PHENIX results on J/ψ production in Au+Au and Cu+Cu collisions at √SNN=200 GeV

Heavy quarkonia production is predicted to be sensitive to the formation of the quark gluon plasma in relativistic heavy ion collisions via competing mechanisms such as color screening and/or quark recombination. During 2004 and 2005 RHIC data taking periods, the PHENIX collaboration has measured J/psi decay into lepton pairs both at mid and forward rapidity in Au+Au and Cu+Cu collisions at root s(NN) = 200 GeV. We present the J/psi nuclear modification factor and the J/psi mean square transverse momentum as a function of the collision centrality for both systems, as well as the rapidity dependence of the J/psi yield for different centrality classes. It is compared to different theoretical predictions. All Au+Au and Cu+Cu results shown here are preliminary.