Realizing scale-invariant density perturbations in low-energy effective string theory
Realizing scale-invariant density perturbations in low-energy effective string theory
复制标题
DOI：
10.1103/physrevd.75.023520
复制
发表时间：
2006-11
影响因子：
5
通讯作者：
Zongkuan Guo;N. Ohta;S. Tsujikawa
中科院分区：
文献类型：
--
作者：
Zongkuan Guo;N. Ohta;S. Tsujikawa
我们讨论了在低能有效弦理论中暴胀和由此产生的宇宙学扰动的实现。为了获得密度扰动的近标度不变谱和抑制的张量-标量比，通常需要将玻色子场{phi}与重力有效地解耦，并存在缓慢变化的玻色子势。我们还研究了二阶修正对树能级作用量的影响，它是耦合到{phi}的Gauss-Bonnet项和动力学项（{nabla}{phi}）{sup 4}的总和。我们发现，它是可能实现观测支持的标量和张量微扰谱的条件下，校正是由（{nabla}{phi}）{sup 4}项，即使在没有的介子势。当Gauss-Bonnet项占主导地位时，尽管可以实现标度不变的标量扰动，但张量扰动在小尺度上关于de Sitter背景表现出剧烈的负不稳定性。
We discuss the realization of inflation and resulting cosmological perturbations in the low-energy effective string theory. In order to obtain nearly scale-invariant spectra of density perturbations and a suppressed tensor-to-scalar ratio, it is generally necessary that the dilaton field {phi} is effectively decoupled from gravity together with the existence of a slowly varying dilaton potential. We also study the effect of second-order corrections to the tree-level action which are the sum of a Gauss-Bonnet term coupled to {phi} and a kinetic term ({nabla}{phi}){sup 4}. We find that it is possible to realize observationally supported spectra of scalar and tensor perturbations provided that the correction is dominated by the ({nabla}{phi}){sup 4} term even in the absence of the dilaton potential. When the Gauss-Bonnet term is dominant, tensor perturbations exhibit violent negative instabilities on small scales about a de Sitter background in spite of the fact that scale-invariant scalar perturbations can be achieved.