  In ultrarelativistic heavy ion collisions, charm quark fragmentation is
modified due to the melting of strings inside the high density partonic matter.
D mesons produced in hadronization can further produce J/psi particles. Using a
multiphase transport model, we investigate the effect on the rapidity
distribution of the produced J/psi particles with two different charm quark
fragmentation functions. It is shown that the J/psi rapidity distribution is
sensitive to the nuclear modification of charm quark fragmentation and thus is
a good indicator of the onset of string melting and the production of
deconfined partonic matter.
