The nonperturbative contribution to asymptotic masses.

In gauge theories, charged particles obey modified dispersion due to medium interactions (forward scattering), leading at high energies $E \geq T$ to an asymptotic mass-squared $m^2_\infty$. We calculate the infrared part of this mass nonperturbatively for the theory of the strong interactions, QCD, through a lattice treatment of its low-energy effective description, Electrostatic QCD (EQCD). Incorporation of these results into a nonperturbative determination of the effective thermal mass will require a still-incomplete next-to-leading order perturbative matching of this quantity to full QCD.