A non-Gaussian landscape

Abstract

Primordial perturbations with wavelengths greater than the observable universe shift the effective background fields in our observable patch from their global averages over the inflating space. This leads to a landscape picture where the properties of our observable patch depend on its location and may significantly differ from the expectation values predicted by the underlying fundamental inflationary model. We show that if multiple fields are present during inflation, this may happen even if our horizon exit would be preceded by only a few e-foldings of inflation. Non-Gaussian statistics are especially affected: for example models of local non-Gaussianity predicting |f_NL|>> 10 over the entire inflating volume can have a probability up to a few tens of percent to generate a non-detectable bispectrum in our observable patch |fNL^{obs.}|<10. In this work we establish systematic connections between the observable local properties of primordial perturbations and the global properties of the inflating space which reflect the underlying high energy physics. We study in detail the implications of both a detection and non-detection of primordial non-Gaussianity by Planck, and discover novel ways of characterising the naturalness of different observational configurations.

21 pages, 6 figures

References in corpus (15)

• Non-Gaussianity in the modulated reheating scenario
• Primordial trispectrum from inflation
• Gauge field production in SUGRA inflation: local non-Gaussianity and primordial black holes
• Semiclassical relations and IR effects in de Sitter and slow-roll space-times
• Angular Trispectrum of CMB Temperature Anisotropy from Primordial Non-Gaussianity with the Full Radiation Transfer Function
• Probing String Theory with Modulated Cosmological Fluctuations
• Scale-dependent non-Gaussianity probes inflationary physics
• Running Kinetic Inflation
• CMB Constraints on Primordial non-Gaussianity from the Bispectrum (f_{NL}) and Trispectrum (g_{NL} and τ_{NL}) and a New Consistency Test of Single-Field Inflation
• The curvature perturbation in a box
• On Classification of Models of Large Local-Type Non-Gaussianity
• IR divergence does not affect the gauge-invariant curvature perturbation
• Inflationary Infrared Divergences: Geometry of the Reheating Surface vs. delta N Formalism
• Statistical Naturalness and non-Gaussianity in a Finite Universe
• Impact of Uncertainties in the Cosmological Parameters on the Measurement of Primordial non-Gaussianity

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• Robust μ-distortion constraints on primordial supermassive black holes from cubic (gNL) non-Gaussian perturbations
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• On the space of non-Gaussian fields with single-clock bispectra
• Beyond the Hubble scale: Super cosmic variance and nongaussianity as a portal to the superhorizon
• Spatial averaging and a non-Gaussianity