标题： 引力子非高斯性在$α$真空中的表现 显示英文标题

标题： Graviton non-gaussianity in $α$-vacuum

摘要： 我们计算了广义$\alpha$-真空在广义相对论中的德西特空间中张量扰动的主导阶非高斯性，即三阶谱。 除了众所周知的邦奇-戴维斯（BD）真空外，还存在由实参数$\alpha$和相位$\phi$表示的无限多个德西特不变真空，其中$\alpha=0$是 BD 真空。 它们被称为$\alpha$-真空。 在标准慢滚暴胀中，由于德西特对称性不再适用，$\alpha$-真空在严格意义上失去了相关性。 尽管如此，如果我们假设参数$\alpha$仅与波数弱相关，并且具有适当的紫外截止，我们可以考虑伪$\alpha$真空。 在虚假真空暴胀的情况下，背景时空是纯德西特时空，非平凡（非BD）的$\alpha$真空确实可以实现。 我们发现一个引人注目的结果，即即使谱密度太小而无法被探测到，双谱也可能被指数级增强以被观测到。 显示英文摘要

摘要： We compute the leading order non-Gaussianity, i.e., the bispectrum, of the tensor perturbation in the general $\alpha$-vacuum on de Sitter space in general relativity. In addition to the well-known Bunch-Davies (BD) vacuum, there exits an infinite number of de Sitter invariant vacua represented by a real parameter $\alpha$ and a phase $\phi$, with $\alpha=0$ being the BD vacuum. They are called $\alpha$-vacua. In the standard slow-roll inflation, as de Sitter invariance no longer applies, the $\alpha$-vacua lose its relevance in the rigorous sense. Nevertheless, if we assume that the parameter $\alpha$ is only weakly dependent on the wavenumber with an appropriate UV cutoff, we may consider pseudo-$\alpha$-vacua. In the case of false vacuum inflation where the background spacetime is pure de Sitter, a non-trivial (non-BD) $\alpha$-vacuum could indeed be realized. We find an intriguing result that the bispectrum may be exponentially enhanced to be detectable by observation even if the spectrum is too small to be detected.