The basic building blocks of QCD are the Green’s functions of the fundamental physical degrees of freedom, gluons and quarks, and of the unphysical ghosts. Even though it is well-known that these quantities are not physical, since they depend on the gauge-fixing scheme and parameters used to quantize the theory, it is widely believed that QCD Green’s functions encode crucial information about the infrared dynamics of the theory. Due to recent improvements in the lattice simulation and the truncation schemes employed for the Schwinger-Dyson equations we have now reached a point where the interplay between these two non-perturbative tools can be most fruitful. In this talk several of the above points will be reviewed, with particular emphasis on the implications for the gluonic and ghost sectors, the non-perturbative effective charge of QCD and the chiral symmetry breaking.
