### Abstract

We develop a theory of nonlinear cosmological perturbations on superhorizon scales for a multi-component scalar field with a general kinetic term and a general form of the potential in the context of inationary cosmology. We employ the ADM for- malism and the spatial gradient expansion approach, characterised by O(ε^{2}), where ε = 1=(HL) is a small parameter representing the ratio of the Hubble radius to the characteristic length scale L of perturbations. We provide a formalism to obtain the solution in the multi field case, if we know a complete set of solution of scalar fields. This formalism can be applied to the calculation of the superhorizon evolution of a primordial non-Gaussianity beyond the so-called δN formalism, equivalent to O(ε^{0}).

Original language | English |
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Pages | 182-185 |

Number of pages | 4 |

Publication status | Published - 2011 Jan 1 |

Event | 21st Workshop on General Relativity and Gravitation in Japan, JGRG 2011 - Sendai, Japan Duration: 2011 Sep 26 → 2011 Sep 29 |

### Other

Other | 21st Workshop on General Relativity and Gravitation in Japan, JGRG 2011 |
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Country | Japan |

City | Sendai |

Period | 11/9/26 → 11/9/29 |

### ASJC Scopus subject areas

- Atomic and Molecular Physics, and Optics

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## Cite this

*Gradient expansion approach to multi-field ination*. 182-185. Paper presented at 21st Workshop on General Relativity and Gravitation in Japan, JGRG 2011, Sendai, Japan.