标题： Genesis-Starobinsky inflation can explain the ACT data 显示英文标题

标题： Genesis--Starobinsky inflation can explain the ACT data

摘要： 我们提出了一种新颖的非奇异宇宙学场景，在Horndeski引力框架内，由三个连续阶段组成：(i) 创世阶段，其中宇宙从渐近平坦的时空缓慢膨胀；(ii) 一个短暂的过渡阶段，恢复广义相对论；以及(iii) Starobinsky暴胀阶段。 该构造在可行参数空间内完全一致：它保持弱耦合，没有鬼魂和梯度不稳定性，整个演化过程中张量扰动速度为光速，标量扰动速度低于光速。 重要的是，创世阶段对Starobinsky势产生了特征性修正，这些修正无法通过简单的$\sum_i c_i R^i$型修改来捕捉。 这些修正稳健地增强了标量谱指数，从而改善了Starobinsky暴胀与最近的CMB测量结果的一致性，特别是来自阿塔卡马宇宙学望远镜（ACT）的数据。 显示英文摘要

摘要： We propose a novel non-singular cosmological scenario within the framework of Horndeski gravity, consisting of three successive stages: (i) a Genesis phase, in which the Universe slowly expands from an asymptotically flat spacetime; (ii) a brief transition stage restoring General Relativity; and (iii) a Starobinsky inflationary phase. This construction is fully consistent within a viable parameter space: it remains weakly coupled, free from ghost and gradient instabilities, with luminal tensor and subluminal scalar perturbations throughout the entire evolution. Importantly, the Genesis phase induces characteristic corrections to the Starobinsky potential, which cannot be captured by simple $\sum_i c_i R^i$-type modifications. These corrections robustly enhance the scalar spectral index, thereby improving the agreement of Starobinsky inflation with recent CMB measurements, in particular the data from the Atacama Cosmology Telescope (ACT).