An in-medium heavy-quark potential from the QQ¯ free energy

We investigate the problem of extracting a static potential between a quark and its antiquark in a quark–gluon plasma (QGP) from lattice-QCD computations of the singlet free energy, FQQ¯(r). We utilize the thermodynamic T  -matrix formalism to calculate the free energy from an underlying potential ansatz resummed in ladder approximation. Imaginary parts of both QQ¯ potential-type and single-quark self-energies are included as estimated from earlier results of the T-matrix approach. We find that the imaginary parts, and in particular their (low-)energy dependence, induce marked deviations of the (real part of the) potential from the calculated free energy. When fitting lattice results of the latter, the extracted potential is characterized by significant long-range contributions from remnants of the confining force. We briefly discuss consequences of this feature for the heavy-quark transport coefficient in the QGP.