Considering an anisotropic cosmological background is an interesting and simultaneously challenging problem of theoretical physics, since we not only assume a high degree of anisotropy in the early stages of the Universe, but also observe it to a small degree until now. In this paper we have constructed the unconstrained action for the perturbations above Bianchi I type background in the most general scalar-tensor theory of gravity, the Horndeski theory, and evaluate the effect of the deviation from the anisotropic background on the previously established stable solution obtained in previous works.

中文翻译：

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各向异性宇宙学背景下 Horndeski 理论的扰动

考虑各向异性宇宙学背景是理论物理学中一个有趣且同时具有挑战性的问题，因为我们不仅假设宇宙的早期阶段具有高度的各向异性，而且到目前为止还小程度地观察到了它。在本文中，我们在最一般的重力标量张量理论——Horndeski理论中构造了Bianchi I型背景以上扰动的无约束作用，并评估了偏离各向异性背景对先前建立的稳定解的影响。在之前的作品中。