发表机构
Pontificia Universidad Católica del Perú（秘鲁天主教 Pontificia 大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究重新评估Belle II超出作为ALP介导热暗物质的解释，引入新测量和可见衰变搜索后，发现标准宇宙学仅窄窗口可行；考虑低温再加热熵注入稀释遗迹丰度，以更小耦合显著改善模型兼容性。
AI 中文摘要
Belle II实验报告了在$B^+\to K^+\nu\bar\nu$衰变中相对于标准模型预言存在$2.7\sigma$的超出，最近被解释为源于一个类轴子粒子（ALP）介导的热暗物质候选者。我们利用同一数据集的新质量微分测量结果重新评估了这一解释，并加入了早期分析中遗漏的两个可见衰变搜索。由此得到的约束使得标准宇宙学历史下的预言仅与超出勉强兼容，在参数空间的狭窄窗口内可行。因此，我们考虑暗物质在低温再加热时期冻结的情况，其特征是熵注入稀释了遗迹丰度。这需要比标准宇宙学中更小的耦合常数，以匹配观测到的暗物质密度，从而打开了参数空间中模型与Belle II超出兼容性显著改善的区域。
英文摘要
Belle II has reported a $2.7σ$ excess in $B^+\to K^+ν\barν$ over its Standard Model prediction, recently interpreted as arising from an axion-like particle mediating a thermal dark matter candidate. We reassess this interpretation using a new mass-differential measurement of the same data set and adding two visible-decay searches that earlier analyses omitted. The resulting bounds leave the predictions from a standard cosmological history only marginally compatible with the excess, viable in a narrow window of parameter space. Thus, we consider a situation where dark matter freezes out during a low-temperature reheating era, featuring entropy injection diluting the relic abundance. This requires smaller couplings compared to those in standard cosmology in order to match the observed dark matter density, opening a region of parameter space where the compatibility of the model with the Belle II excess is significantly improved.
Comments23 pages + references, 6 figures
