Toward a solution to the $R_{AA}$ and $v_2$ puzzle for heavy quarks

Understand

The heavy quarks constitutes a unique probe of the quark-gluon plasma properties.

• Both at RHIC and LHC energies a puzzling relation between the nuclear modification factor $R_{AA}(p_T)$ and the elliptic flow $v_2(p_T)$ has been observed which challenged all the existing models, especially for D mesons.
• We discuss how the temperature dependence of the heavy quark drag coefficient is responsible for a large part of such a puzzle.
• In particular, we have considered four different models to evaluate the temperature dependence of drag and diffusion coefficients propagating through a quark gluon plasma (QGP).