发表机构
School of Natural Sciences, Institute for Advanced Study; Instituut voor Theoretische Fysica, KU Leuven; Racah Institute of Physics, The Hebrew University of Jerusalem; ORFE Department, Princeton University; Institute for Theoretical Physics, University of Amsterdam（高等研究院自然科学学院; 荷语鲁汶大学理论物理研究所; 耶路撒冷希伯来大学拉卡物理学研究所; 普林斯顿大学运筹与金融工程系的; 阿姆斯特丹大学理论物理研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究识别出德西特轴子虫洞中的“宇宙学项链”解，通过洛伦兹时移轮廓和$(a\ o -a)$冗余，发现单个项链主导，产生有限且与轴子通量无关的熵。
AI 中文摘要
我们研究了三维德西特轴子虫洞，它们对无边界密度矩阵有贡献。我们识别出“宇宙学项链”解：一系列对应于重复反弹的欧几里得鞍点的无限序列。这导致无界的引力熵和发散的路程积分。为补救这一点，我们使用（大部分）洛伦兹时移轮廓来研究引力路程积分。在迷你超空间最速下降分析中，我们发现单个项链占主导，从而产生有限熵。一个关键要素是考虑FLRW路程积分中的$(a\ o -a)$冗余，其中$a$是尺度因子。令人惊讶的是，主导解并非纯欧几里得。其熵被证明与轴子通量无关，并等于空德西特熵。我们还研究了由轴子通量或杨-米尔斯瞬子源的高维项链，并论证了定性相似的结果：单个项链解沿洛伦兹时移轮廓占主导。
英文摘要
We investigate 3d de Sitter axion wormhole which contribute to the no-boundary density matrix. We identify "cosmological necklace" solutions: an infinite series of Euclidean saddles corresponding with repeated bounces. This results in an unbound gravitational entropy, and a divergent path integral. To remedy this, we study the gravitational path integral using a (mostly) Lorentzian lapse contour. Within a minisuperspace steepest-descent analysis, we find that a single necklace dominates, leading to a finite entropy. A crucial element is to take into account an $(a\to -a)$ redundancy in the FLRW path integral, where $a$ is the scale factor. Surprisingly, the dominant solution is not purely Euclidean. Its entropy turns out to be independent of the axion flux, and equals the empty de Sitter entropy. We also study higher-dimensional necklaces, sourced by either an axion flux or by Yang-Mills instantons, and argue for qualitatively similar results: the single necklace solution dominates along a Lorentzian lapse contour.
Comments35 pages, 6 figures
