Generation of large-scale magnetic fields, non-Gaussianity, and
  primordial gravitational waves in inflationary cosmology
  The generation of large-scale magnetic fields in inflationary cosmology is
explored, in particular, in a kind of moduli inflation motivated by racetrack
inflation in the context of the Type IIB string theory. In this model, the
conformal invariance of the hypercharge electromagnetic fields is broken thanks
to the coupling of both the scalar and pseudoscalar fields to the hypercharge
electromagnetic fields. The following three cosmological observable quantities
are first evaluated: The current magnetic field strength on the Hubble horizon
scale, which is much smaller than the upper limit from the back reaction
problem, local non-Gaussianity of the curvature perturbations due to the
existence of the massive gauge fields, and the tensor-to-scalar ratio. It is
explicitly demonstrated that the resultant values of local non-Gaussianity and
the tensor-to-scalar ratio are consistent with the Planck data.
