Large Non-Gaussianity in Slow-Roll Inflation

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, $f_{\mathrm{NL}}^{\mathrm{equil}}\propto 1/c_s^4$, 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, $\varphi \to \varphi +b_{\mu }{x}^{\mu }$, 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.

5 pages

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Cited by in corpus (9)

• Dark-Energy Instabilities induced by Gravitational Waves
• The Effective Theory of Shift-Symmetric Cosmologies
• Primordial non-Gaussianity from ultra slow-roll Galileon inflation
• CMB from EFT
• Consistency relations for large-scale structure in modified gravity and the matter bispectrum
• Simplifying the EFT of Inflation: Generalized Disformal Transformations and Redundant Couplings
• Primordial Black Holes from Effective Field Theory of Stochastic Single Field Inflation at NNNLO
• Constraints on Single-Field Inflation
• Scale-dependence in DHOST inflation