Large non-Gaussianity in multiple-field inflation

By G. Rigopoulos, E. Shellard, B. Tent. 2005

138 citations recorded by the source corpus.

We investigate non-Gaussianity in general multiple-field inflation using the formalism we developed in earlier papers. We use a perturbative expansion of the nonlinear equations to calculate the three-point correlator of the curvature perturbation analytically. We derive a general expression that involves only a time integral over background and linear perturbation quantities. We work out this expression explicitly for the two-field slow-roll case, and find that non-Gaussianity can be orders of magnitude larger than in the single-field case. In particular, the bispectrum divided by the square of the power spectrum can easily be of $\mathcal{O}(1--10)$, depending on the model. Our result also shows the explicit momentum dependence of the bispectrum. This conclusion of large non-Gaussianity is confirmed in a semianalytic investigation of a simple quadratic two-field model.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/daee501834d6bc71d0ee580804c6e8d1f344113f

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

1. Xingang Chen
2. M. Zaldarriaga
3. A. Banday
4. F. Vernizzi
5. E. Komatsu
6. J. Fergusson
7. L. Senatore
8. D. Baumann

In Nuclear and High Energy Physics

1. Xingang Chen
2. F. Vernizzi
3. D. Langlois
4. D. Wands
5. M. Zaldarriaga
6. D. Seery
7. E. Sefusatti
8. J. Fergusson

Citations in the corpus

• COrE (Cosmic Origins Explorer) A White Paper (2011, background): “, [100, 101, 102, 103]); models with non-canonical kinetic term [88] (as, e.”
• General CMB and primordial bispectrum estimation: Mode expansion, map making, and measures of F NL (2009, unknown): “This leaves a two-dimensional space on which it is most elegant to use the two independent variables α̃, β̃ [14, 19] α̃ = (k2 − k3)/k̃ , β̃ = (k̃ − k1)/k̃ , where k̃ = 12(k1 + k2 + k3) = const.”
• Primordial Non-Gaussianity and Bispectrum Measurements in the Cosmic Microwave Background and Large-Scale Structure (2010, background): “Indeed, it can prove convenient to characterize the bispectrum in terms of the following transverse parameters [6, 7]:”
• Algorithms for bispectra: Forecasting, optimal analysis, and simulation (2006, background): “…(Goldberg & Spergel 1999; Seljak & Zaldarriaga 1999; Spergel & Goldberg 1999; Cooray & Hu 2000; Hu 2000b; Verde & Spergel 2002) and early universe physics (Alishahiha et al. 2004; Rigopoulos et al. 2006, 2007; Chen et al. 2007a,b), which one might wish to study in a data set such as Planck.”
• Primordial non-Gaussianities from multiple-field inflation (2005, result): “The same conclusion was reached by Rigopoulos, Shellard & van Te nt [67].”
• Planck 2018 results. IX. Constraints on primordial non-Gaussianity (2019, background): “This, along with nonlinearities in the transfer mechanism itself, is a potential source of significant NG (Bartolo et al. 2002; Bernardeau & Uzan 2002; Vernizzi & Wands 2006; Rigopoulos et al. 2006, 2007; Lyth & Rodriguez 2005; Tzavara & van Tent 2011; Jung & van Tent 2017).”
• Planck 2015 results. XVII. Constraints on primordial non-Gaussianity (2015, unknown): “…of this transfer mechanism from isocurvature to adiabatic perturbations (Bartolo et al. 2002; Bernardeau & Uzan 2002; Vernizzi & Wands 2006; Rigopoulos et al. 2006, 2007; Lyth & Rodriguez 2005; Tzavara & van Tent 2011; for a review on NG from multiple-field inflation models, see Byrnes &…”
• Non-linear isocurvature perturbations and non-Gaussianities (2008, methodology): “The adiabatic curvature perturbations generated by this model have been computed in [11, 38, 39] and their non-Gaussianity in [40, 41, 42] (see also [43]).”