PHENIX results on jpsi production in Au+Au and Cu+Cu collisions at   $\sqrt{s_{NN}}$=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 jpsi decay into lepton pairs both at mid and forward rapidity in Au+Au and Cu+Cu collisions at $\sqrt{s_{NN}}$=200 GeV. We present the jpsi nuclear modification factor and the $\jpsi$ mean square transverse momentum as a function of the collision centrality for both systems, as well as the rapidity dependence of the jpsi yield for different centrality classes. It is compared to different theoretical predictions. All Au+Au and Cu+Cu results shown here are preliminary. 
H. Pereira Da Costa (DAPNIA, CEA Saclay) (for the PHENIX   collaboration)