### Abstract

We compute the tree-level connected four-point function of the primordial curvature perturbation for a fairly general minimally coupled single field inflationary model, where the inflaton's Lagrangian is a general function of the scalar field and its first derivatives. This model includes K inflation and DBI inflation as particular cases. We show that, at the leading order in the slow-roll expansion and in the small sound speed limit, there are two important tree-level diagrams for the trispectrum. One is a diagram where a scalar mode is exchanged and the other is a diagram where the interaction occurs at a point, i.e. a contact interaction diagram. The scalar exchange contribution is comparable to the contact interaction contribution. For the DBI-inflation model, in the so-called equilateral configuration, the scalar exchange trispectrum is maximized when the angles between the four momentum vectors are equal and in this case the amplitude of the trispectrum from the scalar exchange is 1 order of magnitude higher than the contact interaction trispectrum.

Original language | English |
---|---|

Article number | 043527 |

Journal | Physical Review D - Particles, Fields, Gravitation and Cosmology |

Volume | 80 |

Issue number | 4 |

DOIs | |

Publication status | Published - 2009 Aug 25 |

Externally published | Yes |

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### ASJC Scopus subject areas

- Nuclear and High Energy Physics

### Cite this

*Physical Review D - Particles, Fields, Gravitation and Cosmology*,

*80*(4), [043527]. https://doi.org/10.1103/PhysRevD.80.043527

**Full trispectrum in single field DBI inflation.** / Arroja, Frederico; Mizuno, Shuntaro; Koyama, Kazuya; Tanaka, Takahiro.

Research output: Contribution to journal › Article

*Physical Review D - Particles, Fields, Gravitation and Cosmology*, vol. 80, no. 4, 043527. https://doi.org/10.1103/PhysRevD.80.043527

}

TY - JOUR

T1 - Full trispectrum in single field DBI inflation

AU - Arroja, Frederico

AU - Mizuno, Shuntaro

AU - Koyama, Kazuya

AU - Tanaka, Takahiro

PY - 2009/8/25

Y1 - 2009/8/25

N2 - We compute the tree-level connected four-point function of the primordial curvature perturbation for a fairly general minimally coupled single field inflationary model, where the inflaton's Lagrangian is a general function of the scalar field and its first derivatives. This model includes K inflation and DBI inflation as particular cases. We show that, at the leading order in the slow-roll expansion and in the small sound speed limit, there are two important tree-level diagrams for the trispectrum. One is a diagram where a scalar mode is exchanged and the other is a diagram where the interaction occurs at a point, i.e. a contact interaction diagram. The scalar exchange contribution is comparable to the contact interaction contribution. For the DBI-inflation model, in the so-called equilateral configuration, the scalar exchange trispectrum is maximized when the angles between the four momentum vectors are equal and in this case the amplitude of the trispectrum from the scalar exchange is 1 order of magnitude higher than the contact interaction trispectrum.

AB - We compute the tree-level connected four-point function of the primordial curvature perturbation for a fairly general minimally coupled single field inflationary model, where the inflaton's Lagrangian is a general function of the scalar field and its first derivatives. This model includes K inflation and DBI inflation as particular cases. We show that, at the leading order in the slow-roll expansion and in the small sound speed limit, there are two important tree-level diagrams for the trispectrum. One is a diagram where a scalar mode is exchanged and the other is a diagram where the interaction occurs at a point, i.e. a contact interaction diagram. The scalar exchange contribution is comparable to the contact interaction contribution. For the DBI-inflation model, in the so-called equilateral configuration, the scalar exchange trispectrum is maximized when the angles between the four momentum vectors are equal and in this case the amplitude of the trispectrum from the scalar exchange is 1 order of magnitude higher than the contact interaction trispectrum.

UR - http://www.scopus.com/inward/record.url?scp=69949149862&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=69949149862&partnerID=8YFLogxK

U2 - 10.1103/PhysRevD.80.043527

DO - 10.1103/PhysRevD.80.043527

M3 - Article

AN - SCOPUS:69949149862

VL - 80

JO - Physical review D: Particles and fields

JF - Physical review D: Particles and fields

SN - 0556-2821

IS - 4

M1 - 043527

ER -