Non-gaussianity of inflationary field perturbations from the field equation

Abstract

We calculate the tree-level bispectrum of the inflaton field perturbation directly from the field equations, and construct the corresponding f_NL parameter. Our results agree with previous ones derived from the Lagrangian. We argue that quantum theory should only be used to calculate the correlators when they first become classical a few Hubble times after horizon exit, the classical evolution taking over thereafter.

arXiv comment16 pages, uses iopart.sty. v2: replaced with version accepted by JCAP; minor changes of wording only. v3: supersedes version published by journal; typo fixed in Eq. (20) and updated references. v4: sign errors in Eqs. (32) and (38) corrected

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• Building a Boostless Bootstrap for the Bispectrum
• The Atacama Cosmology Telescope: Physical Properties and Purity of a Galaxy Cluster Sample Selected via the Sunyaev-Zel'dovich Effect
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• Large Tensor Non-Gaussianity from Axion-Gauge Fields Dynamics
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• Cosmology With Many Light Scalar Fields: Stochastic Inflation and Loop Corrections
• Primordial Non-Gaussianities of General Multiple Field Inflation
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• On Features and Nongaussianity from Inflationary Particle Production
• The CMB asymmetry from inflation
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• Primordial Non-Gaussianity and the NRAO VLA Sky Survey
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• The Conformal Limit of Inflation in the Era of CMB Polarimetry
• Second-order matter perturbations in a LambdaCDM cosmology and non-Gaussianity
• Oscillatory features in the curvature power spectrum after a sudden turn of the inflationary trajectory
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• Feeding your Inflaton: Non-Gaussian Signatures of Interaction Structure
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• Numerical calculation of second order perturbations
• Transporting non-Gaussianity from sub to super-horizon scales
• Renormalisation of IR divergences and holography in de Sitter
• Curvature Perturbations from a Massive Vector Curvaton
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• The Primordial Curvature Perturbation from Vector Fields of General non-Abelian Groups
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• The Mass Function of Void Groups as a Probe of the Primordial non-Gaussianity
• Nonlocal Inflation
• Magnetogenesis and the primordial non-gaussianity
• Measuring the Energy Scale of Inflation with Large Scale Structures
• Revisiting non-Gaussianity of multiple-field inflation from the field equation
• Practical tools for third order cosmological perturbations
• Relics of spatial curvature in the primordial non-gaussianity
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• Non-Gaussianity of Inflationary Gravitational Waves from the Field Equation
• Trapping effects in inflation: blue spectrum at small scales
• Observable predictions of generalised inflationary scenarios
• Remarks on non-gaussian fluctuations of the inflaton and constancy of ζoutside the horizon
• Primordial gravitational waves from excited states