title: Non-Gaussianity in axion N-flation models.
abstract: We study perturbations in the multifield axion N-flation model, taking account of the full cosine potential. We find significant differences from previous analyses which made a quadratic approximation to the potential. The tensor-to-scalar ratio and the scalar spectral index move to lower values, which nevertheless provide an acceptable fit to observation. Most significantly, we find that the bispectrum non-Gaussianity parameter f{NL} may be large, typically of order 10 for moderate values of the axion decay constant, increasing to of order 100 for decay constants slightly smaller than the Planck scale. Such a non-Gaussian fraction is detectable. We argue that this property is generic in multifield models of hilltop inflation.
authors.affiliation: Department of Astronomy and Space Science, Kyung Hee University, Yong-in, South Korea.
authors.forename: Soo A
authors.initials: SA
authors.lastname: Kim
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Liddle
authors.forename: David
authors.initials: D
authors.lastname: Seery