Abstract
Canonical models of single-field, slow-roll inflation do not lead to appreciable non-Gaussianity, unless derivative interactions of the inflaton become uncontrollably large. We propose a novel slow-roll scenario where scalar perturbations propagate at a subluminal speed, leading to sizeable equilateral non-Gaussianity, f equilNL ∝ 1/c 4 s , largely insensitive to the ultraviolet physics. The model is based on a low-energy effective theory characterized by weakly broken invariance under internal galileon transformations, ϕ → ϕ + b μ x μ, which protects the properties of perturbations from large quantum corrections. This provides the unique alternative to models such as DBI inflation in generating strongly subluminal/non-Gaussian scalar perturbations.
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Pirtskhalava, D., Santoni, L., Trincherini, E. et al. Large non-gaussianity in slow-roll inflation. J. High Energ. Phys. 2016, 117 (2016). https://doi.org/10.1007/JHEP04(2016)117
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DOI: https://doi.org/10.1007/JHEP04(2016)117