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arXiv 1502.00977gr-qc
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基于Noether对称性的宇宙学可行的模拟$f(R)$和$f(R,T)$理论

Cosmological viable Mimetic $f(R)$ and $f(R,T)$ theories via Noether symmetry

D. Momeni, R. Myrzakulov, E. Güdekli

摘要:

本文从对称性的观点研究了引力的扩展$f(R)$理论。我们简要地研究了两类扩展的$f(R)$理论的Noether对称性:$f(R,T)$理论,其中曲率与能量动量张量的迹非最小地耦合; $T_{μν}$和拟$f (R) $引力,一个具有标量场自由度,但无鬼影且具有内部共形对称性的理论。在这两种情况下,我们写点样拉格朗日平坦的弗里德曼-勒梅特-罗伯逊-沃克(FLRW)宇宙学背景下的普通物质的存在。我们已经证明了在这些可行的$f(R)$引力推广中存在某些具有Noether对称性的模型。作为一个有动机的想法,我们一直在调查的稳定性的解决方案和反弹和$Λ$ CDM模型使用的Noether对称性。我们已经表明,在模拟$f(R)$重力反弹和$Λ$ CDM解决方案是可能的。还研究了一类具有未来奇点的解。

英文摘要:

Extended $f(R)$ theories of gravity have been investigated from the symmetry point of view. We briefly has been investigated Noether symmetry of two types of extended $f(R)$ theories: $f(R,T)$ theory, in which curvature is coupled non minimally to the trace of energy momentum tensor $T_{μν}$ and mimetic $f (R) $ gravity, a theory with a scalar field degree of freedom, but ghost-free and with internal conformal symmetry. In both cases we write point -like Lagrangian for flat Friedmann-Lemaitre-Robertson-Walker (FLRW) cosmological background in the presence of ordinary matter. We have been shown that some classes of models existed with Noether symmetry in these viable extensions of $f(R)$ gravity. As a motivated idea, we have been investigating the stability of the solutions and the bouncing and $Λ$CDM models using the Noether symmetries. We have been shown that in mimetic $f(R)$ gravity bouncing and $Λ$CDM solutions are possible. Also a class of solutions with future singularities has been investigated.

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