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, Ø1 and Ø2, with exponential potentials, -Vi exp(ciØi), 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 = 5c2 j=12, where c j is the exponent of the potential for the field which becomes sub-dominant at late times.
|ホスト出版物のタイトル||Proceedings of the 17th Workshop on General Relativity and Gravitation in Japan, JGRG 2007|
|出版ステータス||Published - 2007|
|イベント||17th Workshop on General Relativity and Gravitation in Japan, JGRG 2007 - Nagoya|
継続期間: 2007 12月 3 → 2007 12月 7
|Other||17th Workshop on General Relativity and Gravitation in Japan, JGRG 2007|
|Period||07/12/3 → 07/12/7|
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