On non-Gaussianities in single-field inflation

By P. Creminelli. 2003

278 citations recorded by the source corpus.

We study the impact of higher dimension operators in the inflaton Lagrangian on the non-Gaussianity of the scalar spectrum. These terms can strongly enhance the effect without spoiling slow-roll, though it is difficult to exceed fNL~1, because the scale which suppresses the operators cannot be too low, if we want the effective field theory description to make sense. In particular we explicitly calculate the three-point function given by an higher derivative interaction of the form (∇)4, which is expected to give the most important contribution. The angular dependence of the result turns out to be quite different from the minimal case without higher dimension operators.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/6ec29b4e922bbf18fb3b2e9295bec7a87d63b52d

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In Astronomy and Astrophysics

1. L. Senatore
2. Xingang Chen
3. M. Zaldarriaga
4. D. Baumann
5. E. Pajer
6. E. Komatsu
7. D. Green
8. Liam McAllister

In Nuclear and High Energy Physics

1. Xingang Chen
2. D. Baumann
3. L. Senatore
4. E. Pajer
5. M. Zaldarriaga
6. Liam McAllister
7. E. Komatsu
8. D. Seery

Citations in the corpus

• Galileon inflation (2010, background): “Corrections to the Gaussian theory arise from at most a few non-renormalizable operators, leading to very small observable departures from purely Gaussian fluctuations [1, 39].”
• Primordial Non-Gaussianities from Inflation Models (2010, background): “In slow-roll inflation models, one can also add higher derivative terms [49, 80].”
• CMB-S4 Science Case, Reference Design, and Project Plan (2019, background): “Single-field slow-roll inflation necessarily produces f equil NL < 1 [102] and therefore any detection of f equil NL ≥ 1 would rule out this large class of models.”
• Primordial Non-Gaussianity and Bispectrum Measurements in the Cosmic Microwave Background and Large-Scale Structure (2010, methodology): “For DBI inflation, this leads to non-Gaussianity being produced with a shape function of the form [10, 11]”
• DBI in the sky (2004, methodology): “The χ modes also have an ordinary dispersion relation (with a suppressed mass (2.6) but unsuppressed spatial momentum as can be seen from the nonabelian DBI action in Appendix A).”
• The shape of non-Gaussianities (2004, background): “(12) vanishes as k2 3 in the limit k3 → 0 [19].”
• Scale-dependent bias induced by local non-Gaussianity: a comparison to N-body simulations (2008, background): “While single inflaton scenarios predict fNL much less than unity, multi-field inflation models can generate fNL ≫ 1 (Linde & Mukhanov 1997; Lyth et al. 2003; Creminelli 2003; Dvali et al. 2004; Zaldarriaga 2004; Arkani-Hamed et al. 2004; Alishahiha et al. 2004).”
• The cosmological bootstrap: inflationary correlators from symmetries and singularities (2018, unknown): “we obtain precisely equation (14) in [102].”
• Primordial non-Gaussianities in single-field inflation (2005, unknown): “Keywords: Cosmological perturbation theory, Inflation, Cosmology of theories beyond the SM, Physics of the early universe astro-ph/0503692”
• Primordial Non-Gaussianity (2019, background): “Vanilla SFSR inflation necessarily produces f equil NL < 1 [27] and therefore any detection of f equil NL ≥ 1 would rule out a large class of models and would imply that inflation is a strongly coupled phenomenon and/or involved more than one field [28–30].”
• Testing Inflation with Large Scale Structure: Connecting Hopes with Reality (2014, background): “we can ask what is the maximum value of f eq, orth NL compatible with the fact that we wish to have a slow rolling solution where the higher derivative term is not important for the background solution φ̇sr ∼ V ′/H [55].”
• Bouncing Cosmologies: Progress and Problems (2016, result): “Such suppressed non-Gaussianities are consistent with the prediction in canonical, single field, slow-roll models of inflation [116, 121].”
• Inflation and String Theory (2014, unknown): “correspondingly small [121,122,264]: ∣∣f equil NL ∣∣ ∼ 1 c(2)s − 1 ≈ X Λ(4) + · · · 1 .”
• General CMB and primordial bispectrum estimation: Mode expansion, map making, and measures of F NL (2009, unknown): “The equilateral shape is not derived directly from a physical model, but was chosen phenomenologically as a good separable approximation to specific models including the non-local part of Maldacena’s original shape [1], as well as non-canonical cases such as higher derivative models [21] and DBI inf”
• Inflationary trispectrum from graviton exchange (2008, background): “However, the curvature perturbation during inflation is subject to quantum interference effects around the time of horizon crossing, and does not admit a simple parameterization in terms of momentum independent-coefficients [22, 4].”