  A distinctive feature observed in lattice simulations of confining nonabelian
gauge theories, such as Quantum Chromodynamics, is the presence of a dynamical
mass for the gauge field in the low energy regime of the theory. In the
Gribov-Zwanziger framework in the Landau gauge, such mass is a consequence of
the generation of the dimension two condensates $\langle A_\mu^aA_\mu^a\rangle$
and $\langle
\bar\varphi_\mu^{ab}\varphi_\mu^{ab}-\bar\omega_\mu^{ab}\omega_\mu^{ab}\rangle$,
where $A$ is the gluon field and the fields $\bar\varphi$, $\varphi$,
$\bar\omega$, and $\omega$ are Zwanziger's auxiliary fields. In this work, we
show that, in the recently developed BRST-invariant version of the Refined
Gribov-Zwanziger theory, these condensates can be introduced in a
BRST-invariant way for a family of $R_\xi$ gauges. Their values are explicitly
computed to first order and turn out to be independent of the gauge parameters
contained in the gauge-fixing condition, as expected from the BRST invariance
of the formulation. This fact supports the possibility of a gauge-parameter
independent nonzero infrared gluon mass, whose value is the same as the one in
the Landau gauge.
