Gravity and non-gravity mediated couplings in multiple-field inflation

Abstract

Mechanisms for the generation of primordial non-Gaussian metric fluctuations in the context of multiple-field inflation are reviewed. As long as kinetic terms remain canonical, it appears that nonlinear couplings inducing non-gaussianities can be split into two types. The extension of the one-field results to multiple degrees of freedom leads to gravity mediated couplings that are ubiquitous but generally modest. Multiple-field inflation offers however the possibility of generating non-gravity mediated coupling in isocurvature directions that can eventually induce large non-Gaussianities in the metric fluctuations. The robustness of the predictions of such models is eventually examined in view of a case study derived from a high-energy physics construction.

14 pages, 3 figures, invited review for CQG issue on non-linear cosmology

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Cited by in corpus (5)

• The Effective Field Theory of Multifield Inflation
• Review of local non-Gaussianity from multi-field inflation
• On the squeezed limit of the bispectrum in general single field inflation
• A geometrical approach to nonlinear perturbations in relativistic cosmology
• General formula for the running of local fNL