Drag and diffusion co-efficients of heavy quarks in hard thermal loop   approximations
  The drag and diffusion coefficients of heavy quarks propagating through quark gluon plasma (QGP) have been evaluated using Hard Thermal Loop (HTL) approximations. The HTL corrections to the relevant propagators and vertices have been considered. It is observed that the magnitudes of both the transport coefficients are changed significantly from values obtained by earlier approaches where either (i) the $t$ channel divergence in T=0 pQCD matrix element is shielded simply by Debye mass. or (ii) only HTL resummed propagator is used ignoring the HTL corrections at the interaction vertices. The implications of these changes in the transport coefficients on the heavy ion phenomenology have been discussed. 
Surasree Mazumder, Trambak Bhattacharyya and Jan-e Alam
hep-ph nucl-th