标题： 类时边界处的量子应力-能量：用宇宙学数据检验一种新的超越$Λ$冷暗物质参数 显示英文标题

标题： Quantum stress-energy at timelike boundaries: testing a new beyond-$Λ$CDM parameter with cosmological data

摘要： 我们分析了类时边界群体的基本宇宙学效应——一种非平凡时空拓扑形式——包含量子应力能量的边界层。 这种量子场真空涨落的积累可以一致地为负且对紫外敏感，提供了一种额外的宇宙能量密度，其强度足以与物质和暗能量相竞争。 对于允许固定共动边界大小的边界条件，这种效应为决定膨胀历史的弗里德曼方程贡献了一个定性上新的项，其尺度因子为$a$时类似于$-1/a$。 它在相对较晚的时间（$a\approx1/2$）自然占主导地位，同时保持了如大爆炸核合成和再结合等已很好地测量的早期宇宙物理现象。 对于一个广泛的参数窗口，边界在整个历史中都可以大于普朗克长度，包括任何可行尺度的暴胀开始时期。 我们分析了包含这一成分的CMB和BAO数据集（普朗克、ACT和DESI），发现略微偏好（$\sim 2\sigma$），并在物理上缓解了当前数据中的紧张关系（包括中微子质量）。 这一新颖参数可融入超越$\Lambda$CDM 的更大物理参数空间，可能起到这一作用，包括负的空间曲率，这可能也由拓扑考虑和混沌动力学所激发。 最后，我们评论了在宇宙中测试这种拓扑形式的其他现象学前景。 显示英文摘要

摘要： We analyze the basic cosmological effects of a population of timelike boundaries -- a form of nontrivial spacetime topology -- containing a boundary layer of quantum stress energy. This accumulation of vacuum fluctuations of quantum fields can be consistently negative and UV sensitive, providing an additional source of cosmic energy density strong enough to compete with matter and dark energy. For boundary conditions enabling a solution with fixed comoving boundary size, this effect contributes a qualitatively new term to the Friedmann equation determining the expansion history, scaling like $-1/a$ for scale factor $a$. It naturally dominates at relatively late times ($a\approx1/2$), while leaving intact well-measured early universe physics such as big bang nucleosynthesis and recombination. For a wide window of parameters, the boundaries can be larger than the Planck length throughout their history, back through the start of inflation at any viable scale. We analyze CMB and BAO data sets (Planck, ACT, and DESI) allowing for this component, finding a slight preference ($\sim 2\sigma$) and a relaxation of current tensions in the data (including the neutrino mass) in a physical manner. This novel parameter fits into a larger space of physical parameters beyond-$\Lambda$CDM that may serve this role, including negative spatial curvature, which may also be motivated by topological considerations and chaotic dynamics. Finally, we comment on additional phenomenological prospects for testing for this form of topology in the universe.