Charm Quark Medium Modification Within a Linearized Boltzmann Approach

John Moreland, Duke University

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Heavy-flavor probes of the quark-gluon plasma (QGP) have yielded a number of surprising results. Due to their large mass and the temperature scale of the collision, it was anticipated that the charm and bottom quarks would interact weakly with the produced medium. It therefore came as a surprise when experimental results for D mesons indicated charm quarks with small RAA and large elliptic flow vn. This suggests that heavy-flavor probes are sensitive to the collective dynamics of the QGP medium, which are now well described by viscous hydrodynamics. What is, however, not so well understood is the value of the coupling of the heavy quarks to the QGP medium. In this study, we couple the evolution of open charm quarks to viscous hydrodynamics using a linearized Boltzmann equation[1] with pQCD-based matrix elements for the heavy-quarks interacting with the QGP medium. We compare the elastic energy loss transport coefficients e and q in this scheme for an infinite medium at finite temperature against those extracted using a Langevin equation, which describes the kinematics of the Boltzmann equation in the limit of small momentum transfer. We also examine the charm response to a thermal medium with fixed velocity profile, and present first results for charm elastic energy loss in a realistic medium described by viscous hydrodynamics coupled to a hadronic afterburner[2]. [1] J. Auvinen, K.J. Eskola and T. Renk, Phys. Rev. C 82, 024906 (2010). [2] H. Song, S.A. Bass and U. Heinz, Phys. Rev. C 83, 024912 (2011).

Abstract Author(s): J.S. Moreland, S.A. Bass