Heavy flavour kinetic equilibration in the confined phase

Abstract

By making use of a non-perturbative definition of a momentum diffusion coefficient as well as Heavy Meson Chiral Perturbation Theory, we investigate the Brownian motion and kinetic equilibration of heavy quark flavours deep in the confined phase. It appears that the momentum diffusion coefficient can be expressed in terms of known low-energy constants; it increases rapidly at temperatures above 50 MeV, behaving as ~ T^7/F_pi^4 for m_pi / pi << T << F_pi, where m_pi and F_pi are the pion mass and decay constant, respectively. The early increase may suggest a broad peak in kappa/T^3 around the QCD crossover. For a more detailed understanding the computation could be generalized in a number of ways.