用宇宙拓扑打破德西特对称性：红外真空自由度的宇宙学作用
Breaking de Sitter Symmetry with Cosmic Topology: Cosmological Role of Infrared Vacuum Freedom
浏览论文内容
中文总结 AI 辅助
本文研究非平凡拓扑破坏德西特对称性时，红外真空自由度对宇宙学的影响，发现零模可贡献宇宙学常数项，影响暴胀与加速膨胀。
中文摘要 AI 辅助
当时空的时空截面具有非平凡拓扑时，通常用于选择Bunch-Davies真空的对称性论证不再保证适用。我们研究了具有环面空间截面的德西特时空中标量场的这一问题。Hadamard条件确保了与平直空间相同的短距离结构，它们是局域的，自然地对紧致化不敏感。相反，我们发现红外扇区受到打破全局德西特不变性的环面等同性的影响，从而消除了通常用于丢弃零模贡献的论证。我们将剩余的零模自由度视为一种有效的拓扑诱导源，并在半经典框架内分析其对暴胀德西特膨胀的影响。我们证明，对于无质量标量场，零模扇区可以包含对能动张量的贡献，其状态方程为$P=-\ ho$，表现为宇宙学常数。因此，驱动早期宇宙德西特相的源不必仅由作用量中的局域项决定，还可以依赖于量子态的红外结构。非平凡拓扑作为德西特对称性破坏的具体实现，将真空选择中原本未固定的红外自由度转化为与半经典膨胀直接相关的贡献。这一贡献可能适用于当前宇宙的加速膨胀。
英文摘要
When spatial sections of spacetime are topologically nontrivial, the symmetry arguments usually used to choose the Bunch-Davies vacuum are no longer guaranteed to apply. We study this problem for a scalar field on de Sitter spacetime with toroidal spatial sections. The Hadamard conditions, which ensure the same short-distance structure as in flat space, are local and naturally insensitive to the compactification. By contrast, we find that the infrared sector is affected by the toroidal identifications that break global de Sitter invariance, thereby removing the usual argument for discarding zero-mode contributions. We treat the remaining zero-mode freedom as an effective topology-induced source and analyze its effects on an inflationary de Sitter expansion within a semiclassical setting. We show that, for a massless scalar, the zero-mode sector can contain a contribution to the stress-energy tensor with equation of state $P=-ρ$, behaving as a cosmological constant. Thus, the source driving an early-Universe de Sitter phase need not be determined solely by local terms in the action, but can also depend on the infrared structure of the quantum state. Nontrivial topology, as a concrete realization of de Sitter symmetry violation, turns the otherwise-unfixed infrared freedom in vacuum selection to a contribution directly relevant to the semiclassical expansion. This contribution could potentially be applicable to the current accelerated expansion of the Universe.
发表机构
- Case Western Reserve University（凯斯西储大学）
- Instituto de Física Teórica (IFT) UAM-CSIC（马德里自治大学-西班牙国家研究委员会理论物理研究所）
- Imperial College London（帝国理工学院）
- INFN, Sezione di Padova（意大利国家核物理研究院帕多瓦分部）
- Università degli Studi di Padova（帕多瓦大学）
- Laboratoire Univers et Théories, Observatoire de Paris, Université PSL, Université Paris Cité, CNRS（巴黎天文台宇宙与理论实验室（巴黎文理研究大学、巴黎西岱大学、法国国家科学研究中心））
机构由 AI 辅助整理，请以论文原文为准。
