Scalar field dark matter and the Higgs field
  We discuss the possibility that dark matter corresponds to an oscillating
scalar field coupled to the Higgs boson. We argue that the initial field
amplitude should generically be of the order of the Hubble parameter during
inflation, as a result of its quasi-de Sitter fluctuations. This implies that
such a field may account for the present dark matter abundance for masses in
the range $10^{-6} - 10^{-4}$ eV, if the tensor-to-scalar ratio is within the
range of planned CMB experiments. We show that such mass values can naturally
be obtained through either Planck-suppressed non-renormalizable interactions
with the Higgs boson or, alternatively, through renormalizable interactions
within the Randall-Sundrum scenario, where the dark matter scalar resides in
the bulk of the warped extra-dimension and the Higgs is confined to the
infrared brane.
