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arXiv 1908.08785gr-qcastro-ph.COhep-th
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暴胀有效场论中的曲率微扰

Curvature Perturbations in the Effective Field Theory of Inflation

Macarena Lagos, Meng-Xiang Lin, Wayne Hu

发表信息：
Phys. Rev. D 100, 123507 (2019)
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摘要：

我们讨论了通常用于单场膨胀的各种规范不变量之间的差异，即同步$ζ_s$，共动$ζ_c$和酉$ζ_u$曲率。我们发现，保守的$ζ_c$的视界外是相当严格的模型，因为它导致保守的$ζ_s$和$ζ_u$，而反过来并不成立。我们用两个暴胀模型：超慢卷（USR）和编织超慢卷（BUSR）来说明这些差异的后果。在USR中，我们证明了在这三个曲率中，只有$ζ_s$在视界外是守恒的，并且我们将这个结果与分离宇宙的概念和$δN$形式主义的使用联系起来。我们发现，即使$ζ_s$是保守的，仍然有一个轻微的破坏的分离宇宙近似的连续性方程。尽管如此，$δN$形式仍然可以用来计算某些规范不变量（如$ζ_u$）的原始功率谱，尽管它在其他规范不变量（如均匀密度曲率）上会失效。在BUSR中，我们证明了$ζ_u$和$ζ_s$在视界外都是守恒的，但取不同的值。此外，由于$ζ_u\not=ζ_c$，我们发现对膨胀后可观察到的曲率波动的预测并不反映膨胀期间视界交叉处的$ζ_c$，而且不仅涉及该时期的$ζ_u$，而且还涉及编织阶段结束的方式。

英文摘要：

We discuss the difference between various gauge-invariant quantities typically used in single-field inflation, namely synchronous $ζ_s$, comoving $ζ_c$, and unitary $ζ_u$ curvatures. We show that conservation of $ζ_c$ outside the horizon is quite restrictive on models as it leads to conservation of $ζ_s$ and $ζ_u$, whereas the reverse does not hold. We illustrate the consequence of these differences with two inflationary models: ultra-slow-roll (USR) and braiding-ultra-slow-roll (BUSR). In USR, we show that out of the three curvatures, only $ζ_s$ is conserved outside the horizon, and we connect this result to the concepts of separate universe and the usage of the $δN$ formalism. We find that even though $ζ_s$ is conserved, there is still a mild violation of the separate universe approximation in the continuity equation. Nevertheless, the $δN$ formalism can still be applied to calculate the primordial power spectrum of some gauge-invariant quantities such as $ζ_u$, although it breaks down for others such as the uniform-density curvature. In BUSR, we show that both $ζ_u$ and $ζ_s$ are conserved outside the horizon, but take different values. Additionally, since $ζ_u\not=ζ_c$ we find that the prediction for observable curvature fluctuations after inflation does not reflect $ζ_c$ at horizon crossing during inflation and moreover involves not just $ζ_u$ at that epoch but also the manner in which the braiding phase ends.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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