  We investigate Landau gauge $SU(3)$ Yang-Mills theory in a systematic vertex
expansion scheme for the effective action with the functional renormalisation
group. Particular focus is put on the dynamical creation of the gluon mass gap
at non-perturbative momenta and the consistent treatment of quadratic
divergences. The non-perturbative ghost and transverse gluon propagators as
well as the momentum-dependent ghost-gluon, three-gluon and four-gluon vertices
are calculated self-consistently with the classical action as only input. The
apparent convergence of the expansion scheme is discussed and within the
errors, our numerical results are in quantitative agreement with available
lattice results.
