Adiabatic perturbations in pre-big bang models: Matching conditions and scale invariance

被引:121
作者
Durrer, R [1 ]
Vernizzi, F [1 ]
机构
[1] Univ Geneva, Dept Phys Theor, CH-1211 Geneva 4, Switzerland
来源
PHYSICAL REVIEW D | 2002年 / 66卷 / 08期
关键词
D O I
10.1103/PhysRevD.66.083503
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
At low energy, the four-dimensional effective action of the ekpyrotic model of the universe is equivalent to a slightly modified version of the pre-big bang model. We discuss cosmological perturbations in these models. In particular we address the issue of matching the perturbations from a collapsing to an expanding phase. We show that, under certain physically motivated and quite generic assumptions on the high energy corrections, one obtains n=0 for the spectrum of scalar perturbations in the original pre-big bang model (with a vanishing potential). With the same assumptions, when an exponential potential for the dilaton is included, a scale invariant spectrum (n=1) of adiabatic scalar perturbations is produced under very generic matching conditions, both in a modified pre-big bang and ekpyrotic scenario. We also derive the resulting spectrum for arbitrary power law scale factors matched to a radiation-dominated era.
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页数:12
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