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arXiv 1107.0813hep-thastro-ph.COgr-qchep-ph
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多速暴胀中的宇宙学扰动动力学

Dynamics of Cosmological Perturbations in Multi-Speed Inflation

Shi Pi, Du Wang

摘要:

研究了具有可分拉格朗日量的多场暴胀理论,其中每个场具有不同的声速。我们发现这些场总是通过引力相互作用在微扰水平上耦合。我们证明,如果微扰场之间的耦合项足够弱,这些场可以被视为一个组合的解耦场,这是类似于正常模式的耦合振荡。借助于这些场,可以通过$δ\mathcal{N}$形式计算视界交叉处的曲率扰动,直到慢变参数的首阶。解释性地,我们考虑了一个多速DBI暴胀模型,并详细计算了其功率谱。结果取决于不同声速的比率,并且当比率偏离1时显示出明显的放大。

英文摘要:

We study a multi-field inflationary theory with separable Lagrangian, which has different speed of sound for each field. We find that the fields always coupled at perturbative level through gravitational interaction. We show that if the coupling terms among the perturbation fields are weak enough, these fields can be treated as a combination of decoupled fields, which are similar to normal modes in coupled oscillation. By virtue of such fields, the curvature perturbation at the horizon-crossing can be calculated up to the leading order of slow variation parameters via $δ\mathcal{N}$ formalism. Explicitly, we consider a model of multi-speed DBI inflation, and calculate the power spectrum in detail. The result depends on the ratio of different speeds of sound, and shows an apparent amplification when the ratio deviates from unity.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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