Dark matter from torsion in Friedmann cosmology
  A cosmological model in an Einstein-Cartan framework endowed with torsion is
studied. For a torsion function assumed to be proportional to Hubble expansion
function, namely $\phi=-\alpha H$, the contribution of torsion function as a
dark matter component is studied in two different approaches. In the first one,
the total matter energy density is altered by torsion coupling $\alpha$, giving
rise to an effective dark matter and cosmological constant terms that reproduce
quite well the flat cosmic concordance model. In the second approach, starting
with just standard baryonic matter plus a cosmological constant term, it is
obtained that the coupling of torsion with baryons and cosmological constant
term naturally gives rise to a dark matter contribution, together a modified
cosmological term. In this model the dark matter sector can be interpreted as
an effective coupling of the torsion function with the ordinary baryonic matter
and cosmological constant. Finally, it is shown that both models are totally
compatible with recent cosmological data from Supernovae and Hubble parameter
measurements.
