What the Infrared Behavior of QCD Green Functions can tell us about   Confinement in the Covariant Gauge
  We review aspects of confinement in the covariant and local description of QCD and discuss to what extend our present knowledge of the infrared behavior of QCD Green functions can support this description. In particular, we emphasize: the positivity violations of transverse gluon and quark states, the Kugo-Ojima confinement criterion, and the conditions necessary to avoid the decomposition property for colored clusters. We summarize how these issues relate to the infrared behavior of the propagators in Landau gauge QCD as extracted from solutions to truncated Dyson-Schwinger equations and lattice simulations. 
Lorenz von Smekal (1) and Reinhard Alkofer (2) ((1) Universitaet   Erlangen-Nuernberg, (2) Universitaet Tuebingen)