Lorentz boost and non-gaussianity in multi-field dbi-inflation

Shuntaro Mizuno, Frederico Arroja, Kazuya Koyama, Takahiro Tanaka

研究成果: Conference contribution

抄録

We show that higher-order actions for cosmological perturbations in the multi-field DBI inflation model are obtained by a Lorentz boost from the rest frame of the brane to the frame where the brane is moving. We confirm that this simple method provides the same third- And fourth- order actions at leading order in slow-roll and in the small sound speed limit as those obtained by the usual ADM formalism. As an application, we compute the leading order connected four-point function of the primordial curvature perturbation coming from the intrinsic fourth-order contact interaction in the multi-field DBI-inflation model. At third order, the interaction Hamiltonian arises purely by the boost from the second-order action in the rest frame of the brane. The boost acts on the adiabatic and entropy modes in the same way thus there exists a symmetry between the adiabatic and entropy modes. But at fourth order this symmetry is broken due to the intrinsic fourth-order action in the rest frame and the difference between the Lagrangian and the interaction Hamiltonian. Therefore, contrary to the three-point function, the momentum dependence of the purely adiabatic component and the components including the entropic contributions are different in the four-point function. This suggests that the trispectrum can distinguish the multi-field DBI-inflation model from the single field DBI inflation model.

本文言語English
ホスト出版物のタイトル12th Marcel Grossmann Meeting on Recent Dev. in Theoretical and Experimental General Relativity, Astrophysics and Relativistic Field Theories - Proc. of the MG 2009 Meeting on General Relativity
ページ1231-1233
ページ数3
出版ステータスPublished - 2012
外部発表はい
イベント12th Marcel Grossmann Meeting on Recent Developments in Theoretical and Experimental General Relativity, Astrophysics and Relativistic Field Theories, MG 2009 - Paris
継続期間: 2009 7 122009 7 18

Other

Other12th Marcel Grossmann Meeting on Recent Developments in Theoretical and Experimental General Relativity, Astrophysics and Relativistic Field Theories, MG 2009
CityParis
Period09/7/1209/7/18

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Nuclear and High Energy Physics

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