Monday, July 22, 2013

1307.5215 (Federico R. Urban)

Pseudoscalar N-flation and axial coupling revisited    [PDF]

Federico R. Urban
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, in this case the anisotropy is also strongly enhanced, and might be incompatible with the isotropic observed sky. Furthermore, large backreaction can develop. These aspects further demand that the scale of inflation is kept to a minimum.
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