Nonperturbative propagators, running coupling, and the dynamical quark mass of Landau gauge QCD

The coupled system of renormalized Dyson-Schwinger equations for the quark, gluon, and ghost propagators of the Landau gauge QCD is solved within truncation schemes. These employ bare as well as nonperturbative Ans\"atze for the vertices such that the running coupling as well as the quark mass function are independent of the renormalization point. The one-loop anomalous dimensions of all propagators are reproduced. Dynamical chiral symmetry breaking is found; the dynamically generated quark mass agrees well with the phenomenological values, and the corresponding results from lattice calculations. The effects of unquenching the system are small. In particular the infrared behavior of the ghost and gluon dressing functions found in previous studies is almost unchanged as long as the number of light flavors is smaller than four.