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arXiv 0910.4097gr-qc
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修正的(但二阶)引力宇宙学

Cosmology of modified (but second order) gravity

Tomi S. Koivisto

摘要:

这是一个简单的回顾修改后的引力宇宙学。引力作用量的一般扩展涉及高阶导数项,这可能导致鬼点和不稳定性。有三种方法可以解决这个问题:Chern-Simons项、一阶变分原理和非定域性。我们考虑最近的宇宙学应用这三类修改的引力模型,特别是暗能量的问题。可行的参数空间可以非常有效地约束,考虑到宇宙学数据从所有时代除了太阳系的测试和稳定性的考虑。我们提出了一些新的意见,所谓的代数标量张量理论,双标量重新制定的非局部行动涉及逆达朗伯,和一个可能的协变配方全息宇宙学与非微扰引力。

英文摘要:

This is a brief review of modified gravity cosmologies. Generically extensions of gravity action involve higher derivative terms, which can result in ghosts and instabilities. There are three ways to circumvent this: Chern-Simons terms, first order variational principle and nonlocality. We consider recent cosmological applications of these three classes of modified gravity models, in particular to the dark energy problem. The viable parameter spaces can be very efficiently constrained by taking into account cosmological data from all epochs in addition to Solar system tests and stability considerations. We make some new remarks concerning so called algebraic scalar-tensor theories, biscalar reformulation of nonlocal actions involving the inverse d'Alembertian, and a possible covariant formulation holographic cosmology with nonperturbative gravity.

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