arXiv 2004.124252020-04gr-qchep-th

$f(\bar{R}, L(X))$ -在具有幂律展开和能量条件的暗能量背景下的引力

$f(\bar{R}, L(X))$-gravity in the context of dark energy with power law expansion and energy conditions

Goutam Manna, Arijit Panda, Aninda Karmakar, Saibal Ray, Md. Rabiul Islam

备注：: 21 pages, 4 figures, 1 Table
DOI：: 10.1088/1674-1137/ac9fbe

摘要：

本文的主旨是在具有Dirac-Born-Infeld（DBI）作用量簇的{ \bf K-}本质涌现几何的框架下，在暗能量的背景下生成$f(\bar{R}, L(X))-$引力的一般形式，其中$\bar{R}$是熟悉的Ricci标量，$L(X)$是具有$X={1\over 2}g^{μν}\nabla_μϕ\nabla_νϕ$的DBI型非正则拉格朗日量，$ϕ$是{ \bf K-}本质标量场.突现引力度规$\bar{G}_{μν}$和著名的引力度规$g_{μν}$不是共形等价的。在背景引力度规的框架下，利用$f(\bar{R}, L(X))$ -引力中的度规形式，结合相应的Friedmann方程，构造了一个修正的场方程。针对$f(\bar{R}, L(X))$的具体选择，采用幂律展开法，推导了修正的Friedmann方程的解。当我们限制自己考虑暗能量密度的值（如$\dotϕ^{2}=\frac{8}{9}=0.888 <1$）时，该模型与宇宙加速阶段的一致性已经得到证明，这表明当前的宇宙是以暗能量为主的。能量密度（$ρ$）、压力（$p$）和状态参数方程（$ω$）的图形图，基于参数值的时间（$t$）有趣地与暗能量支配一致，因此加速特征。我们还提出了一些光的相应的能量条件和约束的$f(\bar{R}, L(X))$理论与一个基本的例子。

英文摘要：

The motto of this work is to generate a general formalism of $f(\bar{R}, L(X))-$gravity in the context of dark energy under the framework of the {\bf K-}essence emergent geometry with the Dirac-Born-Infeld (DBI) variety of action, where $\bar{R}$ is the familiar Ricci scalar, $L(X)$ is the DBI type non-canonical Lagrangian with $X={1\over 2}g^{μν}\nabla_μϕ\nabla_νϕ$ and $ϕ$ is the {\bf K-}essence scalar field. The emergent gravity metric $\bar{G}_{μν}$ and the well known gravitational metric $g_{μν}$ are not conformally equivalent. We have constructed a modified field equation using the metric formalism in $f(\bar{R}, L(X))$-gravity incorporating the corresponding Friedmann equations in the framework of the background gravitational metric which is of Friedmann-Lema{î}tre-Robertson-Walker (FLRW) type. The solution of modified Friedmann equations have been deduced for the specific choice of $f(\bar{R}, L(X))$, which is of Starobinsky-type, using power law expansion method. The consistency of the model with the accelerating phase of the Universe has been shown, when we restrict ourselves to consider the value of the dark energy density, as $\dotϕ^{2}=\frac{8}{9}=0.888 <1$, which indicates that the present Universe is dark energy dominated. Graphical plots for the energy density ($ρ$), pressure ($p$) and equation of state parameter ($ω$) w.r.t. time ($t$) based on parametric values are interestingly consistent with the dark energy domination and hence accelerating features. We also put some light on the corresponding energy conditions and constraints of the $f(\bar{R}, L(X))$ theory with one basic example.

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。

摘要：

英文摘要：

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