论文标题
全息非最小衍生耦合理论中的宇宙学：引力常数的通胀和变化的约束
Cosmology in holographic non-minimal derivative coupling theory: constraints from inflation and variation of gravitational constant
论文作者
论文摘要
我们考虑了使用Hubble Horizon IR截止的Bekenstein-Hawking熵的全息效应，将非最小导数耦合（NMDC）的宇宙学模型具有重力。全息参数$ c $在一个范围内是恒定的，$ 0 \ leq c <1 $。 NMDC效应允许重力常数时间变化。全息密度的定义包括重力常数的时变部分。 NMDC零件降低了$ \ k> 0 $的重力常数强度，而对$ \ k <0 $则相反。全息部分增强了重力强度。我们使用光谱指数和张量量表比来测试模型针对CMB约束。选择电子折叠的数量为$ n \ geq 60 $。电势，$ v = v_0 ϕ^n $，$ n = 2、4 $和$ v = v_0 \ exp {（ - βϕ）} $。 $ \ k $和$ ϕ $的合并参数图表明，功率谱指数的允许区域和张量表与尺度比率并不重叠。 NMDC通货膨胀被排除在外，全息NMDC通货膨胀也被排除在$ 0 <c <1 $的情况下。 NMDC显着改变了动力学的重大解剖结构，即它为加速区域提供了新的后期吸引子轨迹。全息部分显然会影响轨迹的模式。但是，为了影响加速区域的形状，NMDC场必须存在。为了限制后期模型，考虑了重力常数的变化。引力波标准警报器和超新星数据给出了一个约束，$ \ dot {g}/g | _ {t_0} \ lyseSim 3 \ times10^{ - 12} \，\ \，\ \ text {pext {pext {eart}^{ - 1} $ \ cite {zhao：2018gwk} \ text {年}^{ - 1} \，\ gtrsim \，{ - κ} \ dotϕ \ ddot =/{m^2 _ {\ p}}} \，。 $阳性$ \ k $受到青睐，更大的$ c^2 $会导致提升$ \ k $的下限。
We consider a cosmological model of non-minimal derivative coupling (NMDC) to gravity with holographic effect from Bekenstein-Hawking entropy using Hubble horizon IR cutoff. Holographic parameter $c$ is constant in a range, $0 \leq c < 1$. NMDC effect allows gravitational constant to be time-varying. Definition of holographic density include time-varying part of the gravitational constant. NMDC part reduces strength of gravitational constant for $\k > 0$ and opposite for $\k < 0$. The holographic part enhances gravitational strength. We use spectral index and tensor-to-scalar ratio to test the model against CMB constraint. Number of e-folding is chosen to be $N \geq 60$. Potentials, $V = V_0 ϕ^n $ with $n = 2, 4$, and $V = V_0 \exp{(-βϕ)}$ are considered. Combined parametric plots of $\k$ and $ϕ$ show that the allowed regions of the power spectrum index and of the tensor-to-scalar ratio are not overlapping. NMDC inflation is ruled out and the holographic NMDC inflation is also ruled out for $0 < c < 1$. NMDC significantly changes major anatomy of the dynamics, i.e. it gives new late-time attractor trajectories in acceleration regions. The holographic part clearly affects pattern of trajectories. However, for the holographic part to affect shape of the acceleration region, the NMDC field must be in presence. To constrain the model at late time, variation of gravitational constant is considered. Gravitational-wave standard sirens and supernovae data give a constraint, $\dot{G}/G|_{t_0} \lesssim 3\times10^{-12} \, \text{year}^{-1}$ \cite{Zhao:2018gwk} which, for this model, results in $ 10^{-12} \, \text{year}^{-1} \, \gtrsim \, {- κ} \dotϕ\ddotϕ/{M^2_{\p}}\,. $ Positive $\k$ is favored and greater $c^2$ results in lifting up lower bound of $\k$.
