Non-gaussianity in axion Nflation models

Andrew Liddle

Research output: Contribution to journalArticlepeer-review

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 fNL 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.
Original languageEnglish
Article number181302
Number of pages4
JournalPhysical Review Letters
Volume105
Issue number18
Early online date27 Oct 2010
DOIs
Publication statusPublished - 27 Oct 2010

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