Covariant Model for Dynamical Quark Confinement
  Based on a recent manifestly covariant time-ordered approach to the relativistic many-body problem, the quark propagator is defined by a nonlinear Dyson--Schwinger-type integral equation, with a one-gluon loop. The resulting energy-dependent quark mass is such that the propagator is singularity-free for real energies, thus ensuring confinement. The self-energy integral converges without regularization, due to the chiral limit of the quark mass itself. Moreover, the integral determines the low-energy limit of the quark-gluon coupling constant, for which a value of $g^2/4\pi =4.712$ is found. 
Helmut Haberzettl