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 the total energy loss of a charm quark for a static medium has been computed. For the energy range $E\sim (5-10)$ GeV of charm quark, it is found to be almost same order as that of radiative ones estimated to a first order opacity expansion. The collisional energy loss will become much more important for lower energy charm quarks and this feature could be very interesting for phenomenology of hadrons spectra. Using such collisional energy loss rates we estimate the momentum loss distribution employing a Fokker-Planck equation and the total energy loss of a charm quark for an expanding quark-gluon plasma under conditions resembling the RHIC energies. The fractional collisional energy loss is found to be suppressed by a factor of 5 as compared to static case and does not depend linearly on the system size. 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. 
Munshi G. Mustafa