Large non-Gaussianities in single-field inflation

By Xingang Chen, R. Easther, Eugene A. Lim. 2006

386 citations recorded by the source corpus.

We compute the three-point correlation function for a general model of inflation driven by a single, minimally coupled scalar field. Our approach is based on the numerical evaluation of both the perturbation equations and the integrals which contribute to the three-point function. Consequently, we can analyse models where the potential has a ‘feature’, in the vicinity of which the slow roll parameters may take on large, transient values. This introduces both scale and shape dependent non-Gaussianities into the primordial perturbations. As an example of our methodology, we examine the ‘step’ potentials which have been invoked to improve the fit to the glitch in the for , present in both the one-and three-year WMAP (Wilkinson Microwave Anisotropy Probe) data sets. We show that for the typical parameter values, the non-Gaussianities associated with the step are far larger than those in standard slow roll inflation, and may even be within reach of a next generation cosmic microwave background experiment such as Planck. More generally, we use this example to explain that while adding features to a potential can improve the fit to the two-point function, these are generically associated with a greatly enhanced signal at the three-point level. Moreover, this three-point signal will have a very non-trivial shape and scale dependence, which is correlated with the form of the two-point function, and may thus lead to a consistency check on models of inflation with non-smooth potentials.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/c605bdb53ad1f215a865a082313a11e96d1409f4

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. D. Baumann
3. M. Zaldarriaga
4. L. Senatore
5. E. Pajer
6. Marco Peloso
7. Uros Seljak
8. E. Komatsu

In Nuclear and High Energy Physics

1. D. Baumann
2. Xingang Chen
3. Marco Peloso
4. E. Pajer
5. L. Senatore
6. M. Zaldarriaga
7. Lavinia Heisenberg
8. Yi Wang

Citations in the corpus

• Cosmology and Fundamental Physics with the Euclid Satellite (2012, background): “Indeed, one can temporarily break scale-invariance, for instance by introducing features in the potential as in [302].”
• Review of local non-Gaussianity from multi-field inflation (2010, background): “Observably large non-Gaussianity can be obtained by breaking the slow-roll conditions during inflation [14], using extended kinetic terms [15–25], see also the reviews [26, 27], or going beyond models of single-field inflation [11, 28–34] It is natural to consider multiple scalar field since they ar”
• Resonant non-gaussianity (2010, background): “Chen, Easther and Lim have performed a numerical analysis of both scenarios [5,7].”
• Algorithms for bispectra: Forecasting, optimal analysis, and simulation (2006, background): “Various departures from the simplest scenario, however, are thought to produce observable signals (Creminelli 2003; Zaldarriaga 2004; Arkani-Hamed et al. 2004; Alishahiha, Silverstein & Tong 2004; Rigopoulos, Shellard & van Tent 2006, 2007; Chen et al. 2007a; Chen, Easther & Lim 2007b).”
• Building a boostless bootstrap for the bispectrum (2020, background): “[45, 46, 47, 48, 49, 50, 51]), with some exceptions such as for example resonant non-Gaussianity [52, 53, 54, 55, 56, 57, 58, 59].”