J/psi production and suppression in nuclear collisions

In terms of a new QCD factorization formula for J/$\psi$ production, we calculate the J/$\psi$ suppression in nuclear collisions by including the multiple scattering between the pre-J/$\psi$ partonic states and the nuclear medium. We find agreement with all data on J/$\psi$ suppression in hadron-nucleus and nucleus-nucleus collisions, except a couple of points (the ``second drop'') at the highest $E_T$ bins of the new NA50 data.