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arXiv 1006.0281astro-ph.COgr-qchep-phhep-th
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一般修正引力理论中的密度扰动

Density perturbations in general modified gravitational theories

Antonio De Felice, Shinji Mukohyama, Shinji Tsujikawa

摘要:

本文导出了一般拉格朗日密度$f (R,ϕ, X)/2+L_c$的线性宇宙学扰动方程,其中$R$是Ricci标量,$ϕ$是标量场,$X=-(\nabla ϕ)^2/2$是场动能.我们考虑到一个非线性自相互作用项$L_c$最近研究的背景下,“伽利略”宇宙学,保持场方程在二阶。在明确考虑标量场质量的情况下,得到了亚视界尺度下准静态近似下的物质密度扰动方程和引力势方程。我们还推导出与传播速度相关的鬼和拉普拉斯不稳定性的避免条件。我们的分析包括了大多数文献中提出的暗能量的修正引力模型,因此从理论和观测的角度来检验这些模型的可行性是很方便的。

英文摘要:

We derive the equations of linear cosmological perturbations for the general Lagrangian density $f (R,ϕ, X)/2+L_c$, where $R$ is a Ricci scalar, $ϕ$ is a scalar field, and $X=-(\nabla ϕ)^2/2$ is a field kinetic energy. We take into account a nonlinear self-interaction term $L_c$ recently studied in the context of "Galileon" cosmology, which keeps the field equations at second order. Taking into account a scalar-field mass explicitly, the equations of matter density perturbations and gravitational potentials are obtained under a quasi-static approximation on sub-horizon scales. We also derive conditions for the avoidance of ghosts and Laplacian instabilities associated with propagation speeds. Our analysis includes most of modified gravity models of dark energy proposed in literature and thus it is convenient to test the viability of such models from both theoretical and observational points of view.

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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