论文标题
由于通货膨胀期间的声速降低，功率谱的增长
Growth of power spectrum due to decrease of sound speed during inflation
论文作者
论文摘要
我们研究了由于声速较小而导致的曲率扰动的扩增，并发现其起源与超声滚动膨胀完全不同。这是因为当声速很小时，功率谱的增强来自以下事实：尺度上的曲率扰动小于宇宙微波背景（CMB）尺度会变成量表变化，而不是增长会导致Ultraslow-roll填充期间曲率扰动的扩增。在很大程度上，曲率扰动的功率谱仍然是规模不变的，这与CMB的观察结果一致，然后随着规模越来越小，它将具有瞬态的$ k^2 $增长，并最终接近$ k^4 $。因此，可以增强功率谱以生成大量原始黑洞。此外，当曲率扰动的分散性关系中的高阶校正被认为是曲率扰动的功率谱的生长的起源与没有这种校正的情况相同。
We study the amplification of the curvature perturbations due to a small sound speed and find that its origin is different completely from that due to the ultraslow-roll inflation. This is because when the sound speed is very small the enhancement of the power spectrum comes from the fact that the curvature perturbations at the scales smaller than the cosmic microwave background (CMB) scale becomes scale-variant, rather than growing that leads to the amplification of the curvature perturbations during the ultraslow-roll inflation. At large scales the power spectrum of the curvature perturbations remains to be scale invariant, which is consistent with the CMB observations, and then it will have a transient $k^2$ growth and finally approach a $k^4$ growth as the scale becomes smaller and smaller. Thus the power spectrum can be enhanced to generate a sizable amount of primordial black holes. Furthermore, when the high order correction in the dispersion relation of the curvature perturbations is considered the growth of the power spectrum of the curvature perturbations has the same origin as that in the case without this correction.
