We calculate the curvature power spectrum sourced by spectator fields that are excited repeatedly and non-adiabatically during inflation. In the absence of detailed information of the nature of spectator field interactions, we consider an ensemble of models with intervals between the repeated interactions and interaction strengths drawn from simple probabilistic distributions. We show that the curvature power spectra of each member of the ensemble shows rich structure with many features, and there is a large variability between different realizations of the same ensemble. Such features can be probed by the cosmic microwave background (CMB) and large scale structure observations. They can also have implications for primordial black hole formation and CMB spectral distortions. The geometric random walk behavior of the spectator field allows us to calculate the ensemble-averaged power spectrum of curvature perturbations semi-analytically. For sufficiently large stochastic sourcing, the ensemble-averaged power spectrum shows a scale dependence arising from the time spent by modes outside the horizon during the period of particle production, in spite of there being no preferred scale in the underlying model. We find that the magnitude of the ensemble-averaged power spectrum overestimates the typical power spectra in the ensemble because the ensemble distribution of the power spectra is highly non-Gaussian with fat tails.

中文翻译：

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膨胀期间随机粒子产生的曲率扰动

我们计算了由在膨胀过程中反复和非绝热激发的观众场产生的曲率功率谱。在缺乏观众场互动性质的详细信息的情况下，我们考虑一组模型，其中重复互动和互动强度之间的间隔是从简单的概率分布中得出的。我们表明，集成的每个成员的曲率功率谱显示出具有许多特征的丰富结构，并且同一集成的不同实现之间存在很大的可变性。这些特征可以通过宇宙微波背景 (CMB) 和大尺度结构观测来探测。它们还可能对原始黑洞的形成和 CMB 光谱失真产生影响。观众场的几何随机游走行为使我们能够半解析地计算曲率扰动的系综平均功率谱。对于足够大的随机源，集合平均功率谱显示出由粒子产生期间地平线外模式花费的时间引起的尺度依赖性，尽管基础模型中没有首选尺度。我们发现系综平均功率谱的幅值高估了系综中的典型功率谱，因为功率谱的系综分布是高度非高斯的，带有肥尾。尽管在基础模型中没有首选比例，但整体平均功率谱显示出由在粒子产生期间地平线外模式花费的时间引起的比例依赖性。我们发现系综平均功率谱的幅值高估了系综中的典型功率谱，因为功率谱的系综分布是高度非高斯的，带有肥尾。尽管在基础模型中没有首选比例，但整体平均功率谱显示出由在粒子产生期间地平线外模式花费的时间引起的比例依赖性。我们发现系综平均功率谱的幅值高估了系综中的典型功率谱，因为功率谱的系综分布是高度非高斯的，带有肥尾。