Effect of pre-equilibrium phase on RAA and v2 of heavy quarks in heavy ion collisions

Abstract

Heavy quark RAA and v2 has been calculated at Relativistic Heavy Ion Collider energy considering initial conditions with and without pre-equilibrium phase to highlight the effect of the latter on heavy quark observables. The momentum evolution of the heavy quark has been studied by means of the Boltzmann transport equation. To model the pre-equilibrium phase we have used the KLN initial condition. We found that the pre-equilibrium phase impacts the RAA by about 20%–25% whereas the impact on v2 is very negligible. We also calculated heavy quark RAA and v2 in the case of initializations with early thermalized quark–gluon plasma (QGP). We checked that the particular form of the initial spectrum is not very important for RAA, the larger energy density being more important. In fact, comparing the results obtained within the two initializations we found that one can mimic the impact of the pre-equilibrium phase using an early thermalized QGP medium.