Energy Loss of Charm Quarks in the Quark-Gluon Plasma: Collisional vs Radiative

Considering the collisional energy loss rates of heavy quarks from hard light parton interactions we estimate the momentum loss distribution and the total energy loss of a charm quark in the quark gluon plasma. The total collisional energy loss of a charm quark is compared with the medium induced radiative energy loss obtained, recently, by taking into account the opacity expansion with and without the Ter-Mikayelian effect and found to be same order in magnitude for RHIC energy. This could imply that the collision is one of the dominant energy loss mechanisms in the medium. We also investigate the heavy to light hadrons $D/\pi$ ratio at moderately large (5-10) GeV/c transverse momenta and comment on its enhancement