CCDM model from quantum particle creation: constraints on dark matter
  mass
  In this work the results from the quantum process of matter creation have
been used in order to constrain the mass of the dark matter particles in an
accelerated Cold Dark Matter model (Creation Cold Dark Matter, CCDM). In order
to take into account a back reaction effect due to the particle creation
phenomenon, it has been assumed a small deviation $\varepsilon$ for the scale
factor in the matter dominated era of the form $t^{\frac{2}{3}+\varepsilon}$.
Based on recent $H(z)$ data, the best fit values for the mass of dark matter
created particles and the $\varepsilon$ parameter have been found as
$m=1.6\times10^3$ GeV, restricted to a 68.3\% c.l. interval of
($1.5<m<6.3\times10^7$) GeV and $\varepsilon = -0.250^{+0.15}_{-0.096}$ at
68.3\% c.l. For these best fit values the model correctly recovers a transition
from decelerated to accelerated expansion and admits a positive creation rate
near the present era. Contrary to recent works in CCDM models where the
creation rate was phenomenologically derived, here we have used a quantum
mechanical result for the creation rate of real massive scalar particles, given
a self consistent justification for the physical process. This method also
indicates a possible solution to the so called "dark degeneracy", where one can
not distinguish if it is the quantum vacuum contribution or quantum particle
creation which accelerates the Universe expansion.
