J/ψproduction in relativistic heavy ion collisions from a multiphase transport model

Using a multiphase transport model, we study $J/\psi$ production from interactions between charm and anticharm quarks in the initial parton phase and between D and $\overline{D}$ mesons in the final hadron phase of relativistic heavy ion collisions at the relativistic heavy ion collider. Including also the inverse reactions of $J/\psi$ absorption by gluons and light mesons, we find that the net number of $J/\psi$ from the parton and hadron phases is smaller than that expected from the superposition of initial nucleon-nucleon collisions, contrary to the $J/\psi$ enhancement predicted by the kinetic formation model. The production of $J/\psi$ is further suppressed if one includes the color screening effect in the parton phase. We have also studied the dependence of $J/\psi$ production on the charm quark mass and the effective charm meson mass.