发表机构
Tsinghua University; Peking University; Columbia University; Chengdu University of Technology（清华大学; 北京大学; 哥伦比亚大学; 成都理工大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究提出一个受LZ事件启发的双态非弹性暗物质模型，通过类轴子粒子门户耦合，发现暗扇区宇宙学演化可动态选择直接探测中的非弹性散射主导方向，且模型可被对撞机直接探测。
AI 中文摘要
LUX-ZEPLIN (LZ) 实验最近报道的高反冲候选事件，激发了具有非标准运动学和动量依赖相互作用的暗物质场景。我们研究了一个双态非弹性暗物质模型，其中 $\chi_1$ 和 $\chi_2$ 通过与胶子和光子耦合的类轴子粒子 (ALP) 进行非对角耦合。与仅假设今天只存在一种暗物质态的处理方式不同，我们追踪了两种态的宇宙学演化。激发态 $\chi_2$ 的寿命足够长，能够存活至今，其遗迹丰度由暗扇区转换过程 $\chi_2\chi_2\leftrightarrow\chi_1\chi_1$ 决定。我们发现该丰度强烈依赖于暗物质-ALP相互作用的洛伦兹结构：标量跃迁耦合能有效耗尽 $\chi_2$，有利于吸热 $\chi_1 N\to\chi_2 N$ 散射，而赝标量跃迁耦合则保持 $f_2\simeq1/2$，产生以放热 $\chi_2 N\to\chi_1 N$ 下散射为主导的反冲谱。所有四种场景的基准谱都能在观测到的 $250\\,\mathrm{keV}$ 反冲能量附近出现峰值。我们的结果表明，直接探测中非弹性散射的主导方向可以由暗扇区在早期宇宙中的演化动态选择。借助更多数据，年调制测量可以区分这些场景。我们进一步表明，ALP门户可以在对撞机上直接探测。
英文摘要
The recent high-recoil candidate event reported by LUX-ZEPLIN (LZ) motivates dark-matter scenarios with nonstandard kinematics and momentum-dependent interactions. We study a two-state inelastic dark-matter model in which $χ_1$ and $χ_2$ couple off-diagonally to an axion-like particle (ALP) that also couples to gluons and photons. Unlike treatments that assume only one dark-matter state is present today, we track the cosmological evolution of both states. The excited state $χ_2$ is sufficiently long-lived to survive to the present, with its relic fraction determined by the dark-sector conversion process $χ_2χ_2\leftrightarrowχ_1χ_1$. We find that this fraction depends strongly on the Lorentz structure of the DM--ALP interaction: scalar transition couplings efficiently deplete $χ_2$, favoring endothermic $χ_1 N\toχ_2 N$ scattering, whereas pseudoscalar transition couplings preserve $f_2\simeq1/2$, yielding recoil spectra dominated by exothermic $χ_2 N\toχ_1 N$ down-scattering. Benchmark spectra in all four scenarios can peak near the observed recoil energy of $250\,\mathrm{keV}$. Our results demonstrate that the dominant direction of inelastic scattering in direct detection can be dynamically selected by the early-Universe evolution of the dark sector. With additional data, annual modulation measurements could distinguish these scenarios. We further show that the ALP portal can be directly probed at colliders.
Comments9 pages, 4 figures
