  The possibility of introducing non-perturbative infrared effects leading to a
modification of the long distance behavior of gauge theories through a soft
breaking of the BRST invariance is investigated. The method reproduces the
Gribov-Zwanziger action describing the restriction of the domain of integration
in the Feynman path integral to the Gribov region and a model for the dynamical
quark mass generation is presented. The soft symmetry breaking relies on the
introduction of BRST doublets and massive physical parameters, which allow one
to distinguish the infrared region from the ultraviolet one, within the same
theory.
