Graviton non-gaussianity in α-vacuum
Graviton non-gaussianity in α-vacuum
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DOI：
10.1007/jhep08(2022)210
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发表时间：
2022-06
影响因子：
5.4
通讯作者：
S. Kanno;M. Sasaki
中科院分区：
文献类型：
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作者：
S. Kanno;M. Sasaki
计算了广义相对论De Sitter空间上广义α真空张量微扰的导数阶非高斯性，即双谱。除了众所周知的束-戴维斯(BD)真空外，还存在由实参数α和位相ϕ表示的无限多个de Sitter不变真空，其中α=0为BD真空。它们被称为α-Vacua。在标准的慢滚膨胀中，随着德西特不变性不再适用，α真空在严格意义上失去了它的相关性。然而，如果我们假设参数α仅弱地依赖于具有适当UV截止值的波数，我们可以考虑伪α真空。在背景时空为纯de Sitter的虚假真空暴胀的情况下，确实可以实现非平凡(非BD)的α真空。我们发现了一个有趣的结果，即使光谱太小而不能被检测到，双谱也可以指数地增强到可以通过观察来检测。
We compute the leading order non-Gaussianity, ie, the bispectrum, of the tensor perturbation in the general α-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 α and a phase ϕ, with α= 0 being the BD vacuum. They are called α-vacua. In the standard slow-roll inflation, as de Sitter invariance no longer applies, the α-vacua lose its relevance in the rigorous sense. Nevertheless, if we assume that the parameter α is only weakly dependent on the wavenumber with an appropriate UV cutoff, we may consider pseudo-α-vacua. In the case of false vacuum inflation where the background spacetime is pure de Sitter, a non-trivial (non-BD) α-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.