Generation and characterization of large non-Gaussianities in single field inflation
By Xingang Chen, R. Easther, Eugene A. Lim. 2008
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Inflation driven by a single, minimally coupled, slowly rolling field generically yields a negligible primordial non-Gaussianity. We discuss two distinct mechanisms by which a non-trivial potential can generate large non-Gaussianities. Firstly, if the inflaton traverses a feature in the potential, or if the inflationary phase is short enough so that initial transient contributions to the background dynamics have not been erased, modes near horizon crossing can acquire significant non-Gaussianities. Secondly, potentials with small-scale structure may induce significant non-Gaussianities while the relevant modes are deep inside the horizon. The first case includes the ‘step’ potential we previously analyzed while the second ‘resonance’ case is novel. We derive analytic approximations for the three-point terms generated by both mechanisms written as products of functions of the three individual momenta, permitting the use of efficient analysis algorithms. Finally, we present a significantly improved approach to regularizing and numerically evaluating the integrals that contribute to the three-point function.
Subfields: Astronomy and Astrophysics
View Paper: https://www.semanticscholar.org/paper/1897045e6b2c091f18907479173e998a8f9682e1
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In Astronomy and Astrophysics
Citations in the corpus
- Planck 2015 results. XVII. Constraints on primordial non-Gaussianity (2015, neutral): “This periodicity can generate resonances in the inflationary fluctuations with logarithmically-spaced oscillations, creating imprints in the power spectrum, the bispectrum and trispectrum (Chen et al. 2008; Flauger et al. 2010; Hannestad et al. 2010; Flauger & Pajer 2011).”
- Exploring cosmic origins with CORE: Inflation (2016, background): “Resonant models including periodic oscillations in the potential lead to superimposed sinusoidal oscillation in the spectrum and bispectrum [148], as discussed in Section 2.”
- Quasi-Single Field Inflation and Non-Gaussianities (2009, methodology): “One way is to use the integration by part to increase the convergence speed of the integrand at the τ → −∞ end [33].”
- Primordial Non-Gaussianity and Bispectrum Measurements in the Cosmic Microwave Background and Large-Scale Structure (2010, background): “Analytic forms for both these three point functions have been presented in Chen et al. (2008) with one approximation taking the form, S f eat(k1, k2, k3) ∝ sin ( k1 + k2 + k3 k∗ + P ) , (II.29) where k∗ is the associated scale of the feature in question and P is a phase factor.”
- Testing Inflation with Large Scale Structure: Connecting Hopes with Reality (2014, background): “Resonant non-Gaussianity [79] is another related signature of interest, requiring a similarly precise analysis of the bispectrum and higher point correlators[80].”
- The (not so) squeezed limit of the primordial 3-point function (2011, background): “These may appear as periodic modulations of the inflaton potential [24, 25] or as localized features [26, 27, 28].”
- Observable non-gaussianity from gauge field production in slow roll inflation, and a challenging connection with magnetogenesis (2012, background): “A number of models have been constructed which do produce a detectable nongaussian signature, for example using sound speed effects [6], higher derivatives [7], non-vacuum initial conditions [6, 8–10], sharp potential features [11, 12], post-inflationary effects [13, 14], etc.”
- Confronting Lemaitre–Tolman–Bondi models with observational cosmology (2008, background): “Perhaps these voids arise due to large non-perturbative inhomogeneities associated with the stochastic nature of the inflaton evolution [15], or due to large non-Gaussianities in the primordial spectrum coming from inflation that could arise due to phase transitions or in multifield inflation [55, 5”
- Primordial Features as Evidence for Inflation (2011, background): “This is the leading resonance form found by Chen, Easther and Lim (CEL) for inflation [29].”
- Inflation, Cosmic Perturbations and Non-Gaussianities (2013, background): “As a result [215], the shape function is modulated by an oscillation sin[(k1 + k2 + k3)τ∗].”