Cosmology with interaction in the dark sector
  Unless some unknown symmetry in Nature prevents or suppresses a non-minimal
coupling in the dark sector, the dark energy field may interact with the
pressureless component of dark matter. In this paper, we investigate some
cosmological consequences of a general model of interacting dark matter-dark
energy characterized by a dimensionless parameter $\epsilon$. We derive a
coupled scalar field version for this general class of scenarios and carry out
a joint statistical analysis involving SNe Ia data ({Legacy} and {Constitution}
sets), measurements of baryon acoustic oscillation peak at $z = 0.20$ (2dFGRS)
and $z = 0.35$ (SDSS), and measurements of the Hubble evolution $H(z)$. For the
specific case of vacuum decay ($w = -1$), we find that, although physically
forbidden, a transfer of energy from dark matter to dark energy is favored by
the data.
