标题： 弱引力的稳定岛屿 显示英文标题

标题： Stable Islands of Weak Gravity

摘要： 我们对霍恩德斯基引力的现象学进行了探索，重点研究与广义相对论相比产生弱引力的区域。 这封信介绍了一种生成修改引力理论模型的新方法，这些模型在满足稳定性标准的同时产生特定的观测行为，而无需设定固定的参数化方法。 我们从线性霍恩德斯基理论的固有稳定基础上出发，并在最近发布的爱因斯坦-玻尔兹曼求解器mochi_class中实现。 基础函数的时间演化通过高斯过程设计，在生成过程中直接包含稳定性和现象学标准。 在此，我们关注在后期时间抑制大尺度结构增长的弱引力模型。 为了实现这种行为，我们主要专注于设计一个动态的有效普朗克质量，适用于第五力为零的理论。 我们发现霍恩德斯基理论空间中存在广泛的弱引力岛屿。 我们还包括其他特性，如在$z=0$处对引力的修改为零，并将探索扩展到具有非零第五力的引力岛屿。 最后，我们表明，用 DESI$w_0w_a$CDM 最佳拟合模型替换$\Lambda$CDM 膨胀模型也会产生稳定的弱引力岛屿。 显示英文摘要

摘要： We present an exploration of the phenomenology of Horndeski gravity, focusing on regimes that produce weak gravity compared to General Relativity. This letter introduces a novel method to generate models of modified gravity theories that produce a specific observational behaviour while fulfilling stability criteria, without imposing a fixed parametrisation. We start from the inherently stable basis of linear Horndeski theory, implemented in the recently released Einstein-Boltzmann solver mochi_class. The time evolution of the basis functions is designed with Gaussian processes that directly include the stability and phenomenology criteria during the generation. Here, we focus on models with weak gravity that suppress the growth of Large-Scale Structure at late times. To achieve this behaviour, we mainly focus on the design of a dynamical effective Planck mass for theories with a vanishing fifth force. We find a broad range of weak-gravity islands in Horndeski theory space. We also include additional features, like a vanishing modification to gravity at $z=0$, and extend the exploration to islands of gravity with a non-zero fifth force. Finally, we show that replacing the $\Lambda$CDM expansion model by the DESI $w_0w_a$CDM best fit also produces stable islands of weak gravity.