Pseudoscalar N-flation and axial coupling revisited
  We revisit the dynamics of the axial coupling between many N-flatons and an
Abelian gauge field, with special attention to its statistically anisotropic
signal. The anisotropic power spectrum of curvature perturbations associated to
the large wavelength modes of the gauge vector field is generally undetectable,
since the anisotropy is confined to small scales. If the gauge field is the
electromagnetic field, provided that the number of fields participating in the
exponential expansion is large, it could be possible to generate sizable large
scale magnetic fields. However, its spectrum is blue, and appreciable power on
large scales implies an overly strong field on smaller scales, incompatibly
with observations. Furthermore, the anisotropy is also markedly enhanced, and
might be at odds with the isotropic observed sky. These aspects further demand
that the scale of inflation is kept to a minimum.
