Infrared behavior of QCD from the Dyson-Schwinger formalism
  We discuss the properties of two different types of infrared solutions of Landau gauge Yang-Mills theory and argue for one of these (the 'scaling solution'). We furthermore clarify the status of previously obtained results from DSEs on a four-torus. Including quarks we discuss a relation between confinement and dynamical chiral symmetry breaking based on the scaling solution of Yang-Mills theory. An infrared singularity in the quark-gluon vertex allows for a solution of the $U_A$(1) problem along the lines of a mechanism suggested by Kogut and Susskind long ago. 
Christian S. Fischer