Non-Gaussianity in Axion N-flation Models

Kim, Soo A, Liddle, Andrew R and Seery, David (2010) Non-Gaussianity in Axion N-flation Models. Physical Review Letters, 105 (18). ISSN 1050-2947

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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.

Item Type: Article
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Depositing User: Andrew Liddle
Date Deposited: 06 Feb 2012 18:27
Last Modified: 02 Jul 2019 20:50

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