论文标题
部分可观测时空混沌系统的无模型预测
An effective fluid description of scalar-vector-tensor theories under the sub-horizon and quasi-static approximations
论文作者
论文摘要
我们考虑具有二阶运动方程和张量的传播速度等于光速的标量矢量调整器（SVT）理论。在亚称和准静态近似值下，我们找到了有效的暗能流体的分析公式，即声速，各向异性应力以及能量密度和压力。我们利用了我们的一般分析流体描述，表明可以设计SVT宇宙学模型，这些模型在背景级别与$λ$ CDM退化，同时具有重力强度$ g _ {\ rm eff} <g _ {\ rm n} $在后期的时代以及无危险的黑暗能量扰动。我们在广泛使用的Boltzmann求解器类中实现了SVT设计器模型，因此可以针对天体物理观察测试SVT模型。我们针对SVT模型的有效流体方法揭示了声速中的非微不足道行为，并且鉴于宇宙学参数的当前差异，例如$ H_0 $ $ h_0 $和$σ_8$。
We consider scalar-vector-tensor (SVT) theories with second-order equations of motion and tensor propagation speed equivalent to the speed of light. Under the sub-horizon and the quasi-static approximations we find analytical formulae for an effective dark energy fluid, i.e., sound speed, anisotropic stress as well as energy density and pressure. We took advantage of our general, analytical fluid description and showed that it is possible to design SVT cosmological models which are degenerate with $Λ$CDM at the background level while having gravity strength $G_{\rm eff}<G_{\rm N}$ at late-times as well as non-vanishing dark energy perturbations. We implemented SVT designer models in the widely used Boltzmann solver CLASS thus making it possible to test SVT models against astrophysical observations. Our effective fluid approach to SVT models reveals non trivial behaviour in the sound speed and the anisotropic stress well worth an investigation in light of current discrepancies in cosmological parameters such as $H_0$ and $σ_8$.
