Non-Gaussianity from Axion Monodromy Inflation

Abstract

We study the primordial non-Gaussinity predicted from simple models of inflation with a linear potential and superimposed oscillations. This generic form of the potential is predicted by the axion monodromy inflation model, that has recently been proposed as a possible realization of chaotic inflation in string theory, where the monodromy from wrapped branes extends the range of the closed string axions to beyond the Planck scale. The superimposed oscillations in the potential can lead to new signatures in the CMB spectrum and bispectrum. In particular the bispectrum will have a new distinct shape. We calculate the power spectrum and bispectrum of curvature perturbations in the model, as well as make analytic estimates in various limiting cases. From the numerical analysis we find that for a wide range of allowed parameters the model produces a feature in the bispectrum with fnl ~ 50 or larger while the power spectrum is almost featureless. This model is therefore an example of a string-inspired inflationary model which is testable mainly through its non-Gaussian features. Finally we provide a simple analytic fitting formula for the bispectrum which is accurate to approximately 5% in all cases, and easily implementable in codes designed to provide non-Gaussian templates for CMB analyses.

14 pages, 4 figures, added references, and a new figure with the general shape

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Cited by in corpus (19)

• Large Nongaussianity in Axion Inflation
• Gauge Field Production in Axion Inflation: Consequences for Monodromy, non-Gaussianity in the CMB, and Gravitational Waves at Interferometers
• The Observed Squeezed Limit of Cosmological Three-Point Functions
• Halo Clustering with Non-Local Non-Gaussianity
• Non-Gaussianity from Curvatons Revisited
• On Features and Nongaussianity from Inflationary Particle Production
• Oscillations in the inflaton potential: Complete numerical treatment and comparison with the recent and forthcoming CMB datasets
• Large and strong scale dependent bispectrum in single field inflation from a sharp feature in the mass
• Probing the scale dependence of non-Gaussianity with spectral distortions of the cosmic microwave background
• Bispectrum in Single-Field Inflation Beyond Slow-Roll
• Non-Gaussianity in single field models without slow-roll
• Oscillations in the Primordial Bispectrum: Mode Expansion
• A Consistency Relation for Single-Field Inflation with Power Spectrum Oscillations
• The scalar bi-spectrum during preheating in single field inflationary models
• The Probability Distribution for Non-Gaussianity Estimators
• The probability distribution for non-Gaussianity estimators constructed from the CMB trispectrum
• Wigner-Eckart theorem in cosmology: Bispectra for total-angular-momentum waves
• Resonant Reconciliation of Convex Models and the Planck
• On the space of non-Gaussian fields with single-clock bispectra