Impact of Glasma on heavy quark $R_{AA}$ and $v_2$ in nucleus-nucleus collisions at LHC

We study the effect of the strong quasi-classical gluon field produced in the pre-thermal equilibrium stage of ultra-relativistic heavy ion collisions (RHICs) on the evolution of heavy quarks. It is shown that this field leads to an initial enhancement of the nuclear modification factor ($R_{AA}$) of charm quarks at large $p_T$ . After the further evolution in the QGP phase, we find a larger interaction strength, which is necessary to obtain the $R_{AA}$ measured in experiments, compared to the standard drag and diffusion dynamics without the inclusion of this pre-thermal equilibrium stage. Moreover, we find a larger final elliptic flow $\nu_2$ is obtained, that is quite close to the experimental measurements.