  In this work, we report about the determination of nonperturbative OPE
parameters from fits of continuum perturbation theory to the Landau gauge quark
propagator. The propagators are computed numerically using lattice QCD with
Nf=2 dynamical Wilson twisted mass fermions. We use four different values of
the lattice spacing ranging from about 0.1 fm to about 0.05 fm as well as
several quark masses per lattice spacing. This allows us to obtain continuum
results for the chiral condensate and the average up/down quark mass. The main
results are the average up/down quark mass m_q = 3.0(4)(2) MeV at the physical
point and a value of the chiral condensate of -(299(26)(29) MeV)^3 in the
chiral limit, both in the MSbar scheme at 2 GeV. We have also studied
nonperturbative contaminations of our results at small values of the momenta,
which are often interpreted as the contribution of the gluon condensate A^2. We
do see contributions from such terms, which are, however, not stable over the
order in perturbation theory.
