Toward an understanding of the R-AA and nu(2) puzzle for heavy quarks

One of the primary aims of the ongoing nuclear collisions at Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) energies is to create a Quark Gluon Plasma (QGP). The Heavy Quarks (HQ) constitutes a unique probe of the QGP properties. Both at RHIC and LHC energies a puzzling relation between the nuclear modification factor R-AA(p(T)) and the elliptic flow v(2)(p(T)) related to heavy quark has been observed which challenged all the existing models. We discuss how the temperature dependence of the heavy quark drag coefficient can address for a large part of such a puzzle. We have considered four different models to evaluate the temperature dependence of drag and diffusion coefficients propagating through a quark gluon plasma (QGP). All the four different models are set to reproduce the same R-AA(P-T) experimentally observed at RHIC energy. We have found that for the same R-AA(P-T) one can generate 2 - 3 times more nu(2) depending on the temperature dependence of the heavy quark drag coefficient.