Large slow-roll corrections to the bispectrum of noncanonical inflation

Burrage, Clare, Ribeiro, Raquel H and Seery, David (2011) Large slow-roll corrections to the bispectrum of noncanonical inflation. Journal of Cosmology and Astroparticle Physics, 2011 (07). 032. ISSN 1475-7516

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Abstract

Nongaussian statistics are a powerful discriminant between inflationary models, particularly those with noncanonical kinetic terms. Focusing on theories where the Lagrangian is an arbitrary Lorentz-invariant function of a scalar field and its first derivatives, we review and extend the calculation of the observable three-point function. We compute the "next-order" slow-roll corrections to the bispectrum in closed form, and obtain quantitative estimates of their magnitude in DBI and power-law k-inflation. In the DBI case our results enable us to estimate corrections from the shape of the potential and the warp factor: these can be of order several tens of percent. We track the possible sources of large logarithms which can spoil ordinary perturbation theory, and use them to obtain a general formula for the scale dependence of the bispectrum. Our result satisfies the next-order version of Maldacena's consistency condition and an equivalent consistency condition for the scale dependence. We identify a new bispectrum shape available at next-order, which is similar to a shape encountered in Galileon models. If fNL is sufficiently large this shape may be independently detectable.

Item Type: Article
Additional Information: Author list in alphabetical order
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Depositing User: David Seery
Date Deposited: 06 Feb 2012 19:45
Last Modified: 11 Nov 2013 12:46
URI: http://sro.sussex.ac.uk/id/eprint/22036
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