非对称非弹性暗物质与LUX-ZEPLIN事件
Asymmetric Inelastic Dark Matter and the LUX-ZEPLIN event
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中文总结 AI 辅助
提出非对称非弹性暗物质模型，通过原始不对称性抑制太阳湮灭，以解释LZ实验250 keV候选事件，并预测相关直接探测信号。
中文摘要 AI 辅助
最近LUX-ZEPLIN（LZ）实验在高核反冲能量下的搜索报告了一个约250 keV的引人注目的候选事件，这促使人们用非弹性暗物质来解释。然而，一个简单的Higgsino暗物质实现受到太阳中捕获和随后湮灭的强烈约束，这会产生高能中微子通量，被IceCube实验排除。我们提出了一种非对称非弹性暗物质情景，自然地避免了这一矛盾。暗物质主要是一个标准模型单态狄拉克费米子，与一个近简并的电弱双重态弱混合。其原始不对称性由重马约拉纳费米子的CP破坏非平衡衰变产生，这些重马约拉纳费米子由暴胀子衰变非热产生，而对称分量通过暗扇区相互作用被有效耗尽。反粒子丰度的缺失抑制了太阳中暗物质的湮灭，并消除了相关的IceCube约束。单态-双重态结构同时产生了与混合角成正比的非对角Z玻色子耦合，而对角耦合则被其平方抑制。因此，可观测的非弹性散射率可以与弹性散射的严格限制共存。我们发现，对于几百GeV到1 TeV的暗物质质量，质量劈裂为几百keV，混合角低于O$(10^{-2})$，LZ事件可以被容纳。由于遗迹丰度由原始不对称性而非热冻结决定，较轻的暗物质也是可行的，并且可以缓解与LZ高能边带中缺乏事件的潜在矛盾。该框架预测了相关的弹性和非弹性直接探测信号，以及在对撞机和精密实验中的互补特征。
英文摘要
The recent LUX-ZEPLIN (LZ) search at high nuclear-recoil energies reported an intriguing candidate event near 250 keV, motivating interpretations in terms of inelastic dark matter. A simple realization with Higgsino dark matter, however, is strongly constrained by capture and subsequent annihilation in the Sun, which would produce a high-energy neutrino flux excluded by IceCube. We propose an asymmetric inelastic dark-matter scenario that naturally avoids this tension. The dark matter is a predominantly Standard-Model-singlet Dirac fermion that mixes weakly with a nearly degenerate electroweak doublet. Its primordial asymmetry is generated by CP-violating out-of-equilibrium decays of heavy Majorana fermions produced nonthermally from inflaton decays, while the symmetric component is efficiently depleted through dark-sector interactions. The absence of an appreciable antiparticle abundance then suppresses dark-matter annihilation in the Sun and eliminates the associated IceCube constraint. The singlet-doublet structure simultaneously yields an off-diagonal Z-boson coupling proportional to the mixing angle, whereas the diagonal coupling is suppressed by its square. Consequently, an observable inelastic scattering rate can coexist with stringent limits on elastic scattering. We find that the LZ event can be accommodated for dark-matter masses of a few hundred GeV to 1 TeV, with mass splittings of a few hundred keV and mixing angles below O$(10^{-2})$. Since the relic abundance is set by the primordial asymmetry rather than thermal freeze-out, lighter dark matter is also viable and can alleviate the potential tension with the absence of events in the LZ high-energy sideband. This framework predicts correlated elastic and inelastic direct-detection signals, together with complementary signatures at collider and precision experiments.
发表机构
- University of Tokyo（东京大学）
- Kavli Institute for the Physics and Mathematics of the Universe (WPI), UTIAS, The University of Tokyo（宇宙物理与数学研究 Kavli 研究所（WPI）、UTIAS，东京大学）
- Tsung-Dao Lee Institute & School of Physics and Astronomy, Shanghai Jiao Tong University（上海交大李政道研究所及物理与天文学院）
机构由 AI 辅助整理，请以论文原文为准。
