论文标题
几何通胀和用轴$ f（r）$重力的深色能量
Geometric Inflation and Dark Energy with Axion $F(R)$ Gravity
论文作者
论文摘要
在存在弦理论的情况下，我们提出了$ f（r）$重力的模型，它激发了未对准的轴，就像粒子一样，根据规范标量场最小化与重力相结合的粒子，我们研究了模型的宇宙学现象学，主要在后期时代强调。本文的主要结果是，通货膨胀和黑暗能源时代可以通过$ f（r）$重力以几何方式实现，而轴轴是宇宙的暗物质。 $ f（r）$重力模型由$ r^2 $术语组成，当我们展示的那样，该术语在早期的演变中占主导地位，从而产生了可行的通货膨胀现象学，以及$Δ\ ll 1 $ and forate $ \ sim r^δ$ and power Law术语$ \ sim r^Δ$，最终控制了晚期时代。在通货膨胀时代，轴支球场仍然冻结，这是一个因未对准轴而闻名的效果，但是随着宇宙的扩展，轴上轴开始振荡，其能量密度最终在我们显示的情况下以$ρ_A\ sim a^{-3} $的形式缩小。根据红移$ z $适当地重写引力方程之后，我们详细研究了该模型的晚期现象学，并将结果与$λ$ CDM模型和最新的Planck 2018数据进行了比较。如我们所示，小型红移的模型$ 0 <z <5 $在现象学上与$λ$ CDM模型相似，但是在大型红移，在物质统治时代深处，结果与$λ$ CDM模型的结果不同。在后期研究中，我们研究了几个众所周知的能塔数量的行为，例如减速参数，混蛋和$ OM（z）$，我们证明了包含hubble速率较低衍生品的状态基率的行为相似，$λ$ cdm和axion $ cdm和axion $ f（r）$ feverity模型都具有相似的行为。
We present a model of $F(R)$ gravity in the presence of a string theory motivated misalignment axion like particle materialized in terms of a canonical scalar field minimally coupled with gravity, and we study the cosmological phenomenology of the model, emphasizing mainly on the late-time era. The main result of the paper is that inflation and the dark energy era may be realized in a geometric way by an $F(R)$ gravity, while the axion is the dark matter constituent of the Universe. The $F(R)$ gravity model consists of an $R^2$ term, which as we show dominates the evolution during the early time, thus producing a viable inflationary phenomenology, and a power law term $\sim R^δ$ with $δ\ll 1 $ and positive, which eventually controls the late-time era. The axion field remains frozen during the inflationary era, which is an effect known for misalignment axions, but as the Universe expands, the axion starts to oscillate, and its energy density scales eventually as we show, as $ρ_a\sim a^{-3}$. After appropriately rewriting the gravitational equations in terms of the redshift $z$, we study in detail the late-time phenomenology of the model, and we compare the results with the $Λ$CDM model and the latest Planck 2018 data. As we show, the model for small redshifts $0<z<5$ is phenomenologically similar to the $Λ$CDM model, however at large redshifts and deeply in the matter domination era, the results are different from those of the $Λ$CDM model due to the dark energy oscillations. For the late-time study we investigate the behavior of several well-known statefinder quantities, like the deceleration parameter, the jerk and $Om(z)$, and we demonstrate that the statefinders which contain lower derivatives of the Hubble rate have similar behavior for both the $Λ$CDM and the axion $F(R)$ gravity model.
