Precision QCD propagators with dynamical quarks from the Curci-Ferrari model

We evaluate all two-point correlation functions of the Curci-Ferrari (CF) model in four dimensions and in the presence of degenerate fundamental quark flavors. We compare our results to QCD lattice data in the two flavor case for two different values of the pion mass, one that is relatively far from the chiral limit, and one that is closer to the physical value. This work is a natural extension of an earlier investigation in the quenched approximation. Our results confirm that the QCD gluon and ghost dressing functions are well described by a perturbative approach within the CF model. As for the quark sector, our main result is that the quark dressing function is also well captured by the perturbative approach, but only starting at two-loop order, as anticipated in Ref.~\cite{Pelaez:2014mxa}. The quark mass function is also well reproduced if the quarks are not too light. As is well known, this function cannot be described within a purely perturbative approach in the case of too light quarks. We find nonetheless that, provided one allows for a small offset in the UV, the quark mass function is rather well reproduced in the IR, even for physical quark masses. We also find that, for a given quark mass in the UV, the two-loop corrections tend to generate more mass in the infrared than the one-loop corrections.