On the squeezed limit of the bispectrum in general single field inflation

Abstract

We investigate the consistency relation relating the squeezed limit of the bispectrum to the scalar spectral index in single field models of inflation. We give a simple integral formula for the bispectrum in the squeezed limit in terms of the free mode mode functions of the primordial curvature perturbation, in any Lorentz invariant single field model of inflation and without resorting to any approximation, generalizing a recent result obtained by Ganc and Komatsu in the case of canonical kinetic terms. We use our result to verify the consistency relation in an exactly solvable class of models with a non-trivial speed of sound. We then verify the consistency relation at the first non-trivial order in the slow-varying approximation in general single field inflation (a known result) and at second order in this approximation in canonical single field inflation.

28 pages

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• Non-Gaussianity in single field models without slow-roll
• Examining the consistency relations describing the three-point functions involving tensors
• Primordial Stochastic Gravitational Wave Background Anisotropies: in-in Formalization and Applications
• Scale-dependent hemispherical asymmetry from general initial state during inflation
• On primordial trispectrum from exchanging scalar modes in general multiple field inflationary models
• The flavor composition of ultra-high-energy cosmic neutrinos: measurement forecasts for in-ice radio-based EeV neutrino telescopes
• Quantitative classicality in cosmological interactions during inflation
• Non-Gaussianity from Compositeness
• The primordial non-Gaussianities for non-singular Horndeski cosmologies
• Inflationary cross-correlations of a non-minimal spectator and their soft limits
• Bispectrum at NLO in single field inflation: conservation and squeezed limit