Axion Dark Matter and Planck favor non-minimal couplings to gravity
  Constraints on inflationary scenarios and isocurvature perturbations have
excluded the simplest and most generic models of dark matter based on QCD
axions. Considering non-minimal kinetic couplings of scalar fields to gravity
substantially changes this picture. The axion can account for the observed dark
matter density avoiding the overproduction of isocurvature fluctuations.
Finally, we show that assuming the same non-minimal kinetic coupling to the
axion (dark matter) and to the standard model Higgs boson (inflaton) provides a
minimal picture of early time cosmology.
