AI 中文总结
该研究提出缺陷介导转换（DMC）机制，利用宇宙学畴壁作为混合门户产生暗物质，其在重质量 regime 中主导普通 freeze-in 过程，可解释从 keV 下限到畴形成标度的暗物质遗迹丰度。
AI 中文摘要
我们提出了一种暗物质产生的新机制，即缺陷介导转换（Defect-Mediated Conversion，DMC）。宇宙学畴壁的核心可存在标量凝聚体，充当标准模型与暗 sector 之间的混合门户：穿过畴壁的热浴费米子会部分且非热地转换为暗粒子。转换概率由基于畴壁轮廓的单个无量纲混合面积决定，而粒子产额则由畴壁网络的面密度决定。对于轻暗粒子，该概率与入射能量和暗质量均无关，且遗迹丰度会坍缩为单一的质量-耦合关系，范围从 keV 量级的莱曼-阿尔法下限到畴形成标度。对于重暗粒子，转换会将单个入射费米子的能量转化为暗质量，使暗 sector 中质量超过热浴温度和中介质量的暗粒子得以填充。该门户也会产生普通的 freeze-in 过程，但在固定耦合下，DMC 因相干畴壁面积的增强作用而比 freeze-in 过程主导 1 至 2 个数量级，且在 freeze-in 过程失效的重质量 regime 中仍能发挥作用。
英文摘要
We propose a new mechanism for dark matter genesis, \emph{Defect-Mediated Conversion} (DMC). Cosmological domain walls can host a scalar condensate in their core acting as a mixing portal between the Standard Model and a dark sector: thermal-bath fermions crossing the wall are partially and non-thermally converted into dark particles. The conversion probability is governed by a single dimensionless mixing area built from the wall profile, and the yield by the area density of the network. For a light dark particle the probability is independent of both the incident energy and the dark mass, and the relic abundance collapses onto a single mass--coupling relation running from the keV Lyman-$α$ floor to the wall-formation scale. For a heavy one, conversion turns the energy of a single incident fermion into the dark mass, populating dark sectors with masses exceeding both the bath temperature and the mediator mass. The same portal also sources ordinary freeze-in, but DMC, boosted by the coherent wall-area enhancement, dominates it by one to two orders of magnitude at fixed couplings and remains operative in the heavy regime, where freeze-in shuts off.
Comments18 pages, 8 figures
