  In a functional approach to QCD the infrared behaviour of Landau gauge Green
functions is investigated. Positivity violation for, and thus confinement of,
gluons is demonstrated, and the analytic structure of the gluon propagator is
studied. Quark confinement is related to an infrared divergence of the
quark-gluon vertex. In the latter various components are dynamically induced
due to the spontaneous breaking of chiral symmetry. As a result an infrared
finite running coupling in the Yang-Mills sector is derived whereas the running
coupling related to the quark-gluon vertex is infrared divergent. Based on a
truncation for the quark-gluon vertex Dyson-Schwinger equation, which respects
the analytically determined infrared behavior, numerical results for the
coupled system of the quark propagator and vertex Dyson-Schwinger equations are
presented. The resulting quark mass function as well as the vertex function
show only a very weak dependence on the current quark mass in the deep
infrared. From this we infer by an analysis of the quark-quark scattering
kernel a linearly rising quark potential with an almost mass independent string
tension in the case of broken chiral symmetry.
