Ekpyrotic collapse with multiple fields

被引:56
作者
Koyama, Kazuya [1 ]
Wands, David [1 ]
机构
[1] Univ Portsmouth, Inst Cosmol & Gravitat, Portsmouth PO1 2EG, Hants, England
来源
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS | 2007年 / 04期
基金
英国工程与自然科学研究理事会;
关键词
cosmological perturbation theory; string theory and cosmology; physics of the early universe;
D O I
10.1088/1475-7516/2007/04/008
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
A scale-invariant spectrum of isocurvature perturbations is generated during collapse in the scaling solution in models where two or more fields have steep negative exponential potentials. The scale invariance of the spectrum is realized by a tachyonic instability in the isocurvature field. We show that this instability is due to the fact that the scaling solution is a saddle point in the phase space. The late-time attractor is identified with a single-field-dominated ekpyrotic collapse in which a steep blue spectrum for isocurvature perturbations is found. Although quantum fluctuations do not necessarily to disrupt the classical solution, an additional preceding stage is required to establish classical homogeneity.
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页数:12
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