From in-Medium Color Forces to Transport Properties of QGP

Abstract

A thermodynamic quantum many-body T-matrix approach is employed to study the spectral and transport properties of the quark-gluon plasma at moderate temperatures where nonperturbative effects are essential. For the partonic two-body interaction we utilize a QCD-inspired Hamiltonian whose color forces are motivated by the heavy-quark (HQ) limit including remnants of the confining force, and augmented by relativistic corrections. We solve the in-medium parton propagators and T-matrices selfconsistently and resum the skeleton diagrams for the equation of state (EoS) to all orders thereby accounting for the dynamical formation of two-body bound states. Two types solutions for the in-medium potential are found in when fitting to lattice-QCD data for the EoS, HQ free energy and quarkonium correlators: a weakly-coupled scenario (WCS) with a (real part of the) potential close to the free energy, resulting in moderately broadened spectral functions and weak bound states near Tc, and a strongly-coupled scenario (SCS), with a much stronger potential which produces large imaginary parts (“melting” the parton spectral functions) and generates strong bound states near Tc. We calculate pertinent transport coefficients (specific shear viscosity and HQ diffusion coefficient) and argue that their constraints from heavy-ion phenomenology unambiguously favor the strongly-coupled scenario.