# Large non-Gaussianity in multiple-field inflation

## Abstract

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 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.

- Authors:

- Institute for Theoretical Physics, Utrecht University, Postbus 80.195, 3508 TD Utrecht (Netherlands)
- Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge, CB3 0WA (United Kingdom)

- Publication Date:

- OSTI Identifier:
- 20782893

- Resource Type:
- Journal Article

- Resource Relation:
- Journal Name: Physical Review. D, Particles Fields; Journal Volume: 73; Journal Issue: 8; Other Information: DOI: 10.1103/PhysRevD.73.083522; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; COSMOLOGY; DISTURBANCES; ENERGY SPECTRA; EXPANSION; FIELD EQUATIONS; INFLATIONARY UNIVERSE; INTEGRALS; NONLINEAR PROBLEMS

### Citation Formats

```
Rigopoulos, G.I., Shellard, E.P.S., and Tent, B.J.W. van.
```*Large non-Gaussianity in multiple-field inflation*. United States: N. p., 2006.
Web. doi:10.1103/PHYSREVD.73.083522.

```
Rigopoulos, G.I., Shellard, E.P.S., & Tent, B.J.W. van.
```*Large non-Gaussianity in multiple-field inflation*. United States. doi:10.1103/PHYSREVD.73.083522.

```
Rigopoulos, G.I., Shellard, E.P.S., and Tent, B.J.W. van. Sat .
"Large non-Gaussianity in multiple-field inflation". United States.
doi:10.1103/PHYSREVD.73.083522.
```

```
@article{osti_20782893,
```

title = {Large non-Gaussianity in multiple-field inflation},

author = {Rigopoulos, G.I. and Shellard, E.P.S. and Tent, B.J.W. van},

abstractNote = {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 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.},

doi = {10.1103/PHYSREVD.73.083522},

journal = {Physical Review. D, Particles Fields},

number = 8,

volume = 73,

place = {United States},

year = {Sat Apr 15 00:00:00 EDT 2006},

month = {Sat Apr 15 00:00:00 EDT 2006}

}