发表机构
College of Physics, Jiangxi Normal University; National Gravitation Laboratory, Huazhong University of Science and Technology; Department of Physics, Yantai University（江西师范大学物理学院; 华中科技大学引力实验室; 烟台大学物理系）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
研究费米子暗物质两体衰变产生中微子线和光子连续谱，考虑两个基准模型，推导暗物质寿命限制，发现短寿命媒介子中光子约束主导，特定区域中微子线搜索有竞争力或提供主要灵敏度，结论在相关限制下稳定。
AI 中文摘要
我们研究了费米子暗物质的两体衰变，即$\chi(\bar{\chi})\to X+\nu(\bar{\nu})$，其中轻媒介子$X$随后衰变为光子。我们考虑了两个基准模型：具有$a\to\gamma\gamma$的类轴子粒子和具有$A'\to3\gamma$的动力学混合暗矢量。这种衰变拓扑结构从主要衰变中产生一条单色中微子线以及一个宽的次级光子连续谱。该情景的一个关键特征是光子信号取决于媒介子衰变长度，而中微子线是即时产生的，对$X$的后续传播不敏感。我们从当前和预计的MeV伽马射线和中微子搜索中推导暗物质寿命限制，包括银河系和延迟的河外光子贡献。我们发现，对于短寿命媒介子，光子约束通常占主导，而在媒介子传播显著抑制光子信号的区域，中微子线搜索可能具有竞争力或提供主要灵敏度。在仅河外保守限制和银河系空间模糊的简化处理下，这一结论仍然稳定。
英文摘要
We investigate the two-body decay of fermionic dark matter, $χ(\barχ)\to X+ν(\barν)$, where the light mediator $X$ subsequently decays into photons. We consider two benchmark models: an axion-like particle with $a\toγγ$, and a kinetically mixed dark vector with $A'\to3γ$. This decay topology produces a monochromatic neutrino line from the primary decay together with a broad secondary photon continuum. A key feature of the scenario is that the photon signal depends on the mediator decay length, whereas the neutrino line is produced promptly and is insensitive to the subsequent propagation of $X$. We derive dark matter lifetime limits from current and projected MeV gamma-ray and neutrino searches, including both Galactic and delayed extragalactic photon contributions. We find that photon constraints generally dominate for short-lived mediators, while neutrino-line searches can become competitive or provide the leading sensitivity in regions where mediator propagation substantially suppresses the photon signal. This conclusion remains stable under conservative extragalactic-only limits and a simplified treatment of Galactic spatial smearing.
Comments23 pages, 7 figures
