A T-Matrix Calculation for in-Medium Heavy-Quark Gluon Scattering
  The interactions of charm and bottom quarks in a Quark-Gluon Plasma (QGP) are evaluated using a thermodynamic 2-body T-matrix. We specifically focus on heavy-quark (HQ) interactions with thermal gluons with an input potential motivated by lattice-QCD computations of the HQ free energy. The latter is implemented into a field-theoretic ansatz for color-Coulomb and (remnants of) confining interactions. This, in particular, enables to discuss corrections to the potential approach, specifically hard-thermal-loop corrections to the vertices, relativistic corrections deduced from pertinent Feynman diagrams, and a suitable projection on transverse thermal gluons. The resulting potentials are applied to compute scattering amplitudes in different color channels and utilized for a calculation of the corresponding HQ drag coefficient in the QGP. A factor of ~2-3 enhancement over perturbative results is obtained, mainly driven by the resummation in the attractive color-channels. 
Kyle Huggins, Ralf Rapp
hep-ph nucl-ex nucl-th