Healthy imperfect dark matter from effective theory of mimetic cosmological perturbations
Healthy imperfect dark matter from effective theory of mimetic cosmological perturbations
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DOI：
10.1088/1475-7516/2017/07/009
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发表时间：
2017-04
影响因子：
6.4
通讯作者：
S. Hirano;Sakine Nishi;Tsutomu Kobayashi
中科院分区：
文献类型：
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作者：
S. Hirano;Sakine Nishi;Tsutomu Kobayashi
我们研究了最近提出的标量场物质模型的稳定性，称为模拟暗物质或不完美的暗物质。已知具有高阶导数项的模拟物质在标量扰动下会发生梯度不稳定性。为了寻求不完美暗物质的不稳定性扩展，我们发展了一个有效的宇宙学扰动理论，该理论受标量场动力学项的约束。这是通过使用统一的框架一般标量张量理论的基础上ADM形式主义。我们证明，它确实是可以构建一个模型的不完美的暗物质是免费的鬼和梯度不稳定性。作为一个边注，我们还表明，模仿F（ε）理论是困扰与Ostrogradsky不稳定性。
We study the stability of a recently proposed model of scalar-field matter called mimetic dark matter or imperfect dark matter. It has been known that mimetic matter with higher derivative terms suffers from gradient instabilities in scalar perturbations. To seek for an instability-free extension of imperfect dark matter, we develop an effective theory of cosmological perturbations subject to the constraint on the scalar field's kinetic term. This is done by using the unifying framework of general scalar-tensor theories based on the ADM formalism. We demonstrate that it is indeed possible to construct a model of imperfect dark matter which is free from ghost and gradient instabilities. As a side remark, we also show that mimetic F(ℛ) theory is plagued with the Ostrogradsky instability.