Selfconsistent Evaluation of Charm and Charmonium in the Quark-Gluon Plasma

Abstract

A selfconsistent calculation of heavy-quark (HQ) and quarkonium properties in the Quark-Gluon Plasma (QGP) is conducted to quantify flavor transport and color screening in the medium. The main tool is a thermodynamic $T$-matrix approach to compute HQ and quarkonium spectral functions in both scattering and bound-state regimes. The $T$-matrix, in turn, is employed to calculate HQ selfenergies which are implemented into spectral functions beyond the quasiparticle approximation. Charmonium spectral functions are used to evaluate eulcidean-time correlation functions which are compared to results from thermal lattice QCD. The comparisons are performed in various hadronic channels including zero-mode contributions consistently accounting for finite charm-quark width effects. The zero modes are closely related to the charm-quark number susceptibility which is also compared to existing lattice "data". Both the susceptibility and the heavy-light quark $T$-matrix are applied to calculate the thermal charm-quark relaxation rate, or, equivalently, the charm diffusion constant in the QGP. Implications of our findings in the HQ sector for the viscosity-to-entropy-density ratio of the QGP are briefly discussed.

Comments: 13 pages, 5 figures, invited contribution to NJP Focus Issue "Strongly Coupled Quantum Fluids: From Ultracold Quantum Gases to QCD Plasmas"