  The J/psi is considered to be among the most important probes for the
deconfined quark gluon plasma (QGP) created by relativistic heavy ion
collisions. While the J/psi is thought to dissociate in the QGP by Debye color
screening, there are competing effects from cold nuclear matter (CNM),
feed-downs from excited charmonia (chi_c and psi') and bottom quarks, and
regeneration from uncorrelated charm quarks. Measurements that can provide
information to disentangle these effects are presented in this paper.
