Bispectrum in Single-Field Inflation Beyond Slow-Roll

Abstract

We develop an integral form for the bispectrum in general single-field inflation whose domain of validity includes models of inflation where the background evolution is not constrained to be slowly varying everywhere. Our integral form preserves the squeezed-limit consistency relation, allows for fast evaluation of the bispectrum for all triangle configurations expediting the efficient comparison of slow-roll violating models with data, and provides complete and compact slow-roll expressions correct to first order in slow-roll parameters. Motivated by the recent Planck results, we consider as an example a sharp step in the warped-brane tension of DBI inflation and provide analytic solutions for the peak of the resulting bispectrum. For the step in the warp that reproduces the oscillations in the power spectrum favored by the Planck data, the corresponding equilateral bispectrum is both extremely large and highly scale dependent. The bispectrum serves as a means of distinguishing such a model from alternative scenarios that generate otherwise indistinguishable power spectra, such as a step in the potential in canonical single-field inflation.

20 pages, 6 figures (typo in A22 corrected)

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Cited by in corpus (40)

• Features and New Physical Scales in Primordial Observables: Theory and Observation
• Primordial Black Holes and Local Non-Gaussianity in Canonical Inflation
• Frame-dependence of higher-order inflationary observables in scalar-tensor theories
• Inflation with moderately sharp features in the speed of sound: GSR and in-in formalism for power spectrum and bispectrum
• Squeezed bispectrum and one-loop corrections in transient constant-roll inflation
• The Effective Field Theory of Inflation Models with Sharp Features
• Localized correlated features in the CMB power spectrum and primordial bispectrum from a transient reduction in the speed of sound
• Inflationary Steps in the Planck Data
• Numerical evaluation of the bispectrum in multiple field inflation
• On the scalar consistency relation away from slow roll
• Cancellation of quantum corrections on the soft curvature perturbations
• Steps to Reconcile Inflationary Tensor and Scalar Spectra
• Untangling features in the primordial spectra
• Bounds on non-adiabatic evolution in single-field inflation
• Searching for primordial localized features with CMB and LSS spectra
• Numerically evaluating the bispectrum in curved field-space - with PyTransport 2.0
• Examining the consistency relations describing the three-point functions involving tensors
• Consistency relations for sharp features in the primordial spectra
• Fluid Inflation
• Observational constraints on tachyon and DBI inflation
• Numerical evaluation of the three-point scalar-tensor cross-correlations and the tensor bi-spectrum
• Perturbative Unitarity of Inflationary Models with Features
• Direct search for features in the primordial bispectrum
• Sharp inflaton potentials and bi-spectra: Effects of smoothening the discontinuity
• Numerical evaluation of inflationary 3-point functions on curved field space
• Effect of damped oscillations in the inflationary potential
• Consistency relations for sharp inflationary non-Gaussian features
• Why does the effective field theory of inflation work?
• Generalized Slow Roll for Tensors
• Scalar Bispectrum Beyond Slow-Roll in the Unified EFT of Inflation
• Can power spectrum observations rule out slow-roll inflation?
• From Non-trivial Geometries to Power Spectra and Vice Versa
• Numerical prescriptions of early-time divergences of the in-in formalism
• One spectrum to rule them all?
• Optimal bispectrum constraints on single-field models of inflation
• Superimposed Oscillations in Brane Inflation
• Probing Inflation with Precision Bispectra
• Reionization Parameter Inference from 3D Minkowski Functionals of the 21 cm Signals
• Inflation Story: slow-roll and beyond
• The Black Hole Window on Cosmic Inflation