### Abstract

We compute the non-Gaussianity of the curvature perturbation generated by ekpyrotic collapse with multiple fields. The transition from the multi-field scaling solution to a single-field dominated regime converts initial isocurvature field perturbations to an almost scale-invariant comoving curvature perturbation. In the specific model of two fields, φ_{1} and φ_{2}, with exponential potentials, -V_{t} exp(-c _{t}φ_{i}, we calculate the bispectrum of the resulting curvature perturbation. We find that the non-Gaussianity is dominated by non-linear evolution on super-Hubble scales and hence is of the local form. The non-linear parameter of the curvature perturbation is given by f_{NL} = 5c_{j}
^{2}/12, where c_{j} is the exponent of the potential for the field which becomes sub-dominant at late times.

Original language | English |
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Title of host publication | AIP Conference Proceedings |

Pages | 121-125 |

Number of pages | 5 |

Volume | 1040 |

DOIs | |

Publication status | Published - 2008 |

Externally published | Yes |

Event | KEK Cosmophysics Group Inaugural Conference - Accelerators in the Universe, AIU 2008 - Tsukuba Duration: 2008 Mar 12 → 2008 Mar 14 |

### Other

Other | KEK Cosmophysics Group Inaugural Conference - Accelerators in the Universe, AIU 2008 |
---|---|

City | Tsukuba |

Period | 08/3/12 → 08/3/14 |

### Fingerprint

### Keywords

- Cosmological perturbation theory
- String theory and cosmology

### ASJC Scopus subject areas

- Physics and Astronomy(all)

### Cite this

*AIP Conference Proceedings*(Vol. 1040, pp. 121-125) https://doi.org/10.1063/1.2981535

**Primordial non-Gaussianities in new ekpyrotic cosmology.** / Mizuno, Shuntaro; Koyama, Kazuya; Vernizzi, Filippo; Wands, David.

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

*AIP Conference Proceedings.*vol. 1040, pp. 121-125, KEK Cosmophysics Group Inaugural Conference - Accelerators in the Universe, AIU 2008, Tsukuba, 08/3/12. https://doi.org/10.1063/1.2981535

}

TY - GEN

T1 - Primordial non-Gaussianities in new ekpyrotic cosmology

AU - Mizuno, Shuntaro

AU - Koyama, Kazuya

AU - Vernizzi, Filippo

AU - Wands, David

PY - 2008

Y1 - 2008

N2 - We compute the non-Gaussianity of the curvature perturbation generated by ekpyrotic collapse with multiple fields. The transition from the multi-field scaling solution to a single-field dominated regime converts initial isocurvature field perturbations to an almost scale-invariant comoving curvature perturbation. In the specific model of two fields, φ1 and φ2, with exponential potentials, -Vt exp(-c tφi, we calculate the bispectrum of the resulting curvature perturbation. We find that the non-Gaussianity is dominated by non-linear evolution on super-Hubble scales and hence is of the local form. The non-linear parameter of the curvature perturbation is given by fNL = 5cj 2/12, where cj is the exponent of the potential for the field which becomes sub-dominant at late times.

AB - We compute the non-Gaussianity of the curvature perturbation generated by ekpyrotic collapse with multiple fields. The transition from the multi-field scaling solution to a single-field dominated regime converts initial isocurvature field perturbations to an almost scale-invariant comoving curvature perturbation. In the specific model of two fields, φ1 and φ2, with exponential potentials, -Vt exp(-c tφi, we calculate the bispectrum of the resulting curvature perturbation. We find that the non-Gaussianity is dominated by non-linear evolution on super-Hubble scales and hence is of the local form. The non-linear parameter of the curvature perturbation is given by fNL = 5cj 2/12, where cj is the exponent of the potential for the field which becomes sub-dominant at late times.

KW - Cosmological perturbation theory

KW - String theory and cosmology

UR - http://www.scopus.com/inward/record.url?scp=52249097655&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=52249097655&partnerID=8YFLogxK

U2 - 10.1063/1.2981535

DO - 10.1063/1.2981535

M3 - Conference contribution

SN - 9780735405677

VL - 1040

SP - 121

EP - 125

BT - AIP Conference Proceedings

ER -