Phenomenology in minimal theory of massive gravity
Phenomenology in minimal theory of massive gravity
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DOI：
10.1088/1475-7516/2016/04/028
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发表时间：
2015-12
影响因子：
6.4
通讯作者：
A. D. Felice;S. Mukohyama
中科院分区：
文献类型：
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作者：
A. D. Felice;S. Mukohyama
本文研究了最近提出的最小质量引力理论。在回顾了原来的建设的基础上，其哈密顿的vielbein形式主义，我们重新制定它的拉格朗日方面的vielbein和度量形式主义。然后很明显，与以前在洛伦兹破坏的大质量引力文献中的尝试不同，不仅势而且作用的动力学结构都是从de Rham-Gabadadze-Tolley（dRGT）大质量引力理论修改的。我们确认，在完全非线性水平的MTMG的物理自由度的数量是两个。这证明了各种可能的病理，如超发光，因果关系和强耦合的情况下。之后，我们讨论了尘埃流体存在下的MTMG现象。我们发现，在一个平坦的均匀和各向同性的背景，我们有两个分支。其中之一（自加速分支）自然会导致加速，而不需要真正的宇宙学常数或暗能量。对于这个分支，标量和矢量模式的行为完全与广义相对论（GR）中的行为相同。这个分支的现象学在张量模式扇区中不同于GR，因为张量模式获得非零质量。因此，MTMG作为一个稳定的非线性完成的自加速宇宙学解决方案最初发现在dRGT理论。另一个分支（正常分支）具有取决于时间相关的基准度量的动态。对于正常的分支，标量模式扇区，即使在GR中只有一个标量模式存在（由于尘埃流体），不同于GR中的一个，并且，在一般情况下，结构形成将遵循不同的现象。张量模将是有质量的，而矢量模，对于这两个分支，将具有与GR相同的现象。
We investigate the minimal theory of massive gravity (MTMG) recently introduced. After reviewing the original construction based on its Hamiltonian in the vielbein formalism, we reformulate it in terms of its Lagrangian in both the vielbein and the metric formalisms. It then becomes obvious that, unlike previous attempts in the literature of Lorentz-violating massive gravity, not only the potential but also the kinetic structure of the action is modified from the de Rham-Gabadadze-Tolley (dRGT) massive gravity theory. We confirm that the number of physical degrees of freedom in MTMG is two at fully nonlinear level. This proves the absence of various possible pathologies such as superluminality, acausality and strong coupling. Afterwards, we discuss the phenomenology of MTMG in the presence of a dust fluid. We find that on a flat homogeneous and isotropic background we have two branches. One of them (self-accelerating branch) naturally leads to acceleration without the genuine cosmological constant or dark energy. For this branch both the scalar and the vector modes behave exactly as in general relativity (GR). The phenomenology of this branch differs from GR in the tensor modes sector, as the tensor modes acquire a non-zero mass. Hence, MTMG serves as a stable nonlinear completion of the self-accelerating cosmological solution found originally in dRGT theory. The other branch (normal branch) has a dynamics which depends on the time-dependent fiducial metric. For the normal branch, the scalar mode sector, even though as in GR only one scalar mode is present (due to the dust fluid), differs from the one in GR, and, in general, structure formation will follow a different phenomenology. The tensor modes will be massive, whereas the vector modes, for both branches, will have the same phenomenology as in GR.