Sub-horizon perturbations in scalar-tensor theories have been shown to grow generically faster than in uncoupled models due to a positive, additive Yukawa force. In such cases, the amount of clustering becomes larger than in the standard cosmological model, exacerbating the observed tension in the $\sigma_8$ parameter. Here we show instead that in some simple cases of conformally coupled dark energy one can obtain a transient regime of negative Yukawa force, without introducing ghosts or other instabilities.

中文翻译：

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标量张量理论中的瞬态弱引力

标量张量理论中的亚地平线扰动已被证明通常比非耦合模型中的增长更快，这是由于汤川力为正的加性力。在这种情况下，聚类量变得比标准宇宙学模型中的更大，加剧了 $\sigma_8$ 参数中观察到的张力。在这里，我们展示了在一些共形耦合暗能量的简单情况下，人们可以获得负汤川力的瞬态状态，而不会引入鬼影或其他不稳定性。