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arXiv · astro-ph/0509719

Non-Gaussian perturbations from multi-field inflation

Laura E. Allen·Sujata Gupta·David Wands
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Abstract

We show how the primordial bispectrum of density perturbations from inflation may be characterised in terms of manifestly gauge-invariant cosmological perturbations at second order. The primordial metric perturbation, zeta, describing the perturbed expansion of uniform-density hypersurfaces on large scales is related to scalar field perturbations on unperturbed (spatially-flat) hypersurfaces at first- and second-order. The bispectrum of the metric perturbation is thus composed of (i) a local contribution due to the second-order gauge-transformation, and (ii) the instrinsic bispectrum of the field perturbations on spatially flat hypersurfaces. We generalise previous results to allow for scale-dependence of the scalar field power spectra and correlations that can develop between fields on super-Hubble scales.

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Laura E. Allen, Sujata Gupta, David Wands. 2005-12-13. Non-Gaussian perturbations from multi-field inflation. https://doi.org/10.1088/1475-7516%2F2006%2F01%2F006

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