Impact of Glasma on heavy quark observables in nucleus-nucleus collisions at LHC

Understand

In the pre-thermal equilibrium stage of relativistic heavy-ion collisions, a strong quasi-classical transverse gluon field emerges at about $\tau_0 \simeq 0.1 \, \rm fm/c$ and evolves together with their longitudinal counterparts according to the classical Yang-Mills (CYM) equations.

• Recently it has been shown that these fields induce a diffusion of charm quarks in momentum space resulting in a tilt of their spectrum without a significant drag.
• We find that in nucleus-nucleus collisions at LHC such a novel dynamics of charm quarks leads to an initial enhancement of the nuclear modification factor ($R_{AA}$) at $p_T$ larger than 2 GeV$/c$ contrary to the standard lore.
• Moreover, the same dynamics leads to a larger final elliptic flow ($v_2$) inducing a relation between $R_{AA}$ and $v_2$ that is quite close to the experimental measurements.