Gradient expansion approach to multi-field ination

Yuichi Takamizu, Atsushi Naruko, Misao Sasaki

Research output: Contribution to conferencePaperpeer-review


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(ε2), 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(ε0).

Original languageEnglish
Number of pages4
Publication statusPublished - 2011 Jan 1
Event21st Workshop on General Relativity and Gravitation in Japan, JGRG 2011 - Sendai, Japan
Duration: 2011 Sep 262011 Sep 29


Other21st Workshop on General Relativity and Gravitation in Japan, JGRG 2011

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics


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