What the Azimuthal Distribution of Heavy Mesons Tells Us About the Quark Gluon Plasma

Heavy mesons (charm and bottom) are one of the few probes which are sensitive to the time evolution of a Quark Gluon Plasma (QGP), light mesons come to a statistical equilibrium latest at the end of the QGP expansion and do therefore not carry information on the QGP properties during the expansion. We discuss here the interaction of the heavy quarks with the QGP partons and how this interaction influences the azimuthal distribution of the heavy mesons. We will argue that there are indications that small \(p_T\) heavy quarks equilibrate in the QGP whereas those with a high \(p_T\) create a finite azimuthal flow due to the different path lengths in the QGP. These are results of the pQCD based Monte-Carlo (MC@sHQ) approach which is coupled to EPOS 2 modeling the expansion of the QGP.