The inflationary bispectrum with curved field-space

Elliston, Joseph, Seery, David and Tavakol, Reza (2012) The inflationary bispectrum with curved field-space. Journal of Cosmology and Astroparticle Physics, 2012 (11). ISSN 1475-7516

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Abstract

We compute the covariant three-point function near horizon-crossing for a system of slowly-rolling scalar fields during an inflationary epoch, allowing for an arbitrary field-space metric. We show explicitly how to compute its subsequent evolution using a covariantized version of the separate universe or "delta-N" expansion, which must be augmented by terms measuring curvature of the field-space manifold, and give the nonlinear gauge transformation to the comoving curvature perturbation. Nonlinearities induced by the field-space curvature terms are a new and potentially significant source of non-Gaussianity. We show how inflationary models with non-minimal coupling to the spacetime Ricci scalar can be accommodated within this framework. This yields a simple toolkit allowing the bispectrum to be computed in models with non-negligible field-space curvature.

Item Type: Article
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Subjects: Q Science > QB Astronomy > QB0980 Cosmogony. Cosmology
Depositing User: David Seery
Date Deposited: 08 Sep 2014 09:47
Last Modified: 14 Mar 2017 02:22
URI: http://sro.sussex.ac.uk/id/eprint/42470

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