  QCD with two colors undergoes a transition to a superfluid phase with diquark
condensate when the quark chemical potential equals half the pion mass. We
investigate the gluonic aspects of the transition by inspecting the behavior of
the glueball correlators evaluated via a multi-step smearing procedure for
several values of chemical potential ranging between zero and the saturation
threshold. The results are based on an analysis of 0++ glueball correlators, on
a sample of 40000 independent configurations on each parameter set. The
amplitudes of the correlators peak for \mu = m_\pi/2,indicating that the
superfluid phase transition affects the gluonic sector as well. The mass of the
fundamental state decreases in the superfluid phase, and the amplitude of the
propagators drops, suggesting a reduction of the gluon condensate, in agreement
with model calculations. The analysis of the smearing dependence of the results
helps disentangling the role of long and short distance phenomena at the
superfluid transition.
