从 Starobinsky 暴胀中隧穿：提高谱指数
Tunnelling out of Starobinsky inflation: Raising the spectral tilt
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中文总结 AI 辅助
研究提出 Starobinsky 暴胀的混合实现方式，通过双场系统和真空衰变结束暴胀，类似旧暴胀退出，提高标量谱指数 \(n_s\) 并保持小张量与标量比，还留下随机引力波遗迹，为向高 \(n_s\) 区域移动提供简单方法。
中文摘要 AI 辅助
我们提出了一种 Starobinsky 暴胀的混合实现方式，其中暴胀阶段通过真空衰变结束。该模型由一个有效的双场系统组成，具有相对于真实分支发生位移的亚稳 Starobinsky 分支。在可观测阶段，暴胀子沿着虚假分支缓慢滚动，直到在正交方向上的一阶相变将其连接到真实分支并突然结束暴胀。这种类似旧暴胀的退出方式跳过了原本 Starobinsky 轨迹的最后部分。结果，宇宙微波背景的枢轴尺度比普通 Starobinsky 暴胀更远离虚假分支的最小值处退出哈勃半径，提高了标量谱指数 \(n_s\) 同时保持特征性的小张量与标量比。这提供了一种将 Starobinsky 暴胀向近期与 ACT 相关组合所青睐的高 \(n_s\) 区域移动的简单方法。相同的真空转变留下了一个随机引力波遗迹，其峰值频率由隧穿时间尺度和随后的再加热历史控制。
英文摘要
We propose a hybrid realization of Starobinsky inflation in which the inflationary epoch ends through vacuum decay. The model consists of an effective two-field system with a metastable Starobinsky branch shifted with respect to the true one. During the observable stage, the inflaton slow-rolls along the false branch, until a first-order phase transition in an orthogonal direction connects it to the true branch and ends inflation abruptly. This old-inflation-like exit skips the last part of the would-be Starobinsky trajectory. As a result, the Cosmic Microwave Background pivot scale exits the Hubble radius further from the minimum of the false branch than in ordinary Starobinsky inflation, raising the scalar spectral tilt $n_s$ while preserving the characteristic small tensor-to-scalar ratio. This provides a simple way of moving Starobinsky inflation towards the high-$n_s$ region favoured by recent ACT-related combinations. The same vacuum transition leaves a stochastic gravitational-wave relic whose peak frequency is controlled by the tunnelling timescale and the subsequent reheating history.
