Studies of confinement: How quarks and gluons propagate

Using the Schwinger-Dyson equations the behavior of quark and gluon propagators is studied in the Landau gauge for momenta from the deep Euclidean to the confinement regime. We find that while at short distances quarks and gluons propagate like free particles, over longer distances, of the order of a fermi, the gluon propagator is greatly enhanced as are the triple-gluon and quark-gluon couplings. These in turn suppress the propagation of massless quarks over long distances to such an extent that they have no physical particle pole, exactly as expected of a confining theory. We study the way the world changes as the number of massless flavors of quark is increased from zero. Even one generation of light fermions has a sizable deconfining effect on the one-gluon-exchange part of the interquark potential, greater than suggested by naive perturbative counting. These results highlight the usefulness of this continuum approach to nonperturbative QCD as a method of investigating the mechanics of confinement.