We study the effect of adding an interaction in the 𝐺3 term of Horndeski theory, where the propagation of gravitational waves is not modified. We derive the background and perturbation equations of motion from the action. We also derive the no-ghost and Laplacian instability conditions for tensor modes and scalar mode propagation. Then we study the evolution of the matter perturbation in the quasistatic approximation. We find that the gravitational couplings to the baryonic and cold dark matter over density are modified in this theory. We introduce a concrete model of the free function in the theory and study the background and linear perturbation dynamics. We then use the genetic algorithm to test the model. We compare the 𝐻⁡(𝑧) function of the model and the 𝐻⁡(𝑧) curve predicted by the genetic algorithm, using the 𝐻⁡(𝑧) data. For the perturbation sector, we compute the 𝑓⁢𝜎8 observable for the model and compare it with the predicted function from the genetic algorithm from the 𝑓⁢𝜎8 data.

中文翻译：

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G3 相互作用的标量-张量暗能量


我们研究了在 Horndeski 理论的 G3 项中添加相互作用的影响，其中引力波的传播没有改变。我们从动作中推导出运动的背景方程和扰动方程。我们还推导出了张量模式和标量模式传播的无重影和拉普拉斯不稳定性条件。然后，我们研究准静态近似中物质扰动的演变。我们发现，该理论修改了重子和冷暗物质与密度的引力耦合。我们在理论中引入了自由函数的具体模型，并研究了背景和线性微扰动力学。然后，我们使用遗传算法来测试模型。我们使用 H（z） 数据比较模型的 H（z） 函数和遗传算法预测的 H（z） 曲线。对于扰动扇区，我们计算模型的 fσ8 可观测值，并将其与 fσ8 数据中遗传算法的预测函数进行比较。