CCDM Model with Spatial Curvature and The Breaking of "Dark Degeneracy"
  Creation of Cold Dark Matter (CCDM), in the context of Einstein Field
Equations, leads to a negative creation pressure, which can be used to explain
the accelerated expansion of the Universe. Recently, it has been shown that the
dynamics of expansion of such models can not be distinguished from the
concordance $\Lambda$CDM model, even at higher orders in the evolution of
density perturbations, leading at the so called "dark degeneracy". However,
depending on the form of the CDM creation rate, the inclusion of spatial
curvature leads to a different behavior of CCDM when compared to $\Lambda$CDM,
even at background level. With a simple form for the creation rate, namely,
$\Gamma\propto\frac{1}{H}$, we show that this model can be distinguished from
$\Lambda$CDM, provided the Universe has some amount of spatial curvature.
Observationally, however, the current limits on spatial flatness from CMB
indicate that neither of the models are significantly favored against the other
by current data, at least in the background level.
