发表机构
Harvard University; University of Victoria（哈佛大学; 维多利亚大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
研究半经典德西特量子引力中晚期态的重叠，在德西特JT引力形变中计算无边界波函数单圈修正，发现洛伦兹测度配对与欧几里得引力隐含配对的不匹配，讨论其对微扰引力切割粘合的意义。
AI 中文摘要
我们研究半经典德西特量子引力中晚期态的重叠。在德西特JT引力的一类形变中，我们计算了无边界波函数的单圈修正，并推导了超局域晚期测度。单个宇宙对模的贡献恰好是球面振幅的8倍，因此洛伦兹测度所用的配对与欧几里得引力中隐含的配对不同。在对不连通的最终宇宙求和后，无边界模将单个宇宙的结果指数化，得到⟨⟨HH|HH⟩⟩≈exp(8Z_sphere)，而非闭合几何的求和结果Z_closed≈exp(Z_sphere)。我们还回顾了正宇宙学常数的爱因斯坦引力中类似的不匹配，其中晚期无边界模在单圈时消失，与欧几里得球面振幅不同。我们讨论了其对微扰引力中切割与粘合的意义，以及将该构造扩展到拓扑求和时出现的特征。
英文摘要
We study overlaps of late-time states in semiclassical de Sitter quantum gravity. In a family of deformations of de Sitter JT gravity, we compute the no-boundary wavefunction to one-loop and derive the ultralocal late-time measure. The one-universe contribution to the norm is exactly eight times the sphere amplitude, so the pairing used by the Lorentzian measure differs from that implicit in Euclidean gravity. After summing over disconnected final universes, the no-boundary norm exponentiates the one-universe result, giving $\langle \!\langle \text{HH}|\text{HH}\rangle\!\rangle \approx \exp(4Z_{\rm sphere})$ rather than the sum over closed geometries, $Z_{\rm closed}\approx \exp(Z_{\rm sphere})$. We also review an analogous mismatch in Einstein gravity with positive cosmological constant, where the late-time no-boundary norm vanishes at one-loop, differing from the Euclidean sphere amplitude. We discuss the implications for cutting and gluing in perturbative gravity, and features that arise when extending this construction to sums over topologies.
Comments40 pages, 2 figures; v2: factor of 2 fixed, refs added
