发表机构
Yazd University（亚兹德大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究提出一种冻结进入非对称费米子暗物质模型，通过CP破坏衰变产生不对称性，并利用双重角色标量消除对称分量，满足观测丰度且不受当前实验约束。
AI 中文摘要
我们提出了一个最小、可预测的非对称费米子暗物质（DM）通过冻结进入机制产生的场景。标准模型（SM）被扩展，引入了一个作为暗物质候选体的狄拉克费米子ψ、一个辅助狄拉克费米子χ、一个实标量中介子φ和一个更重的实标量S，所有这些都由Z2×Z2'离散对称性稳定。暗物质不对称性是通过中介子φ的CP破坏非平衡衰变产生的，而更重的标量S扮演双重角色：它通过与φ的干涉产生所需的不对称性的物理CP破坏相位，并介导暗物质群体对称分量的湮灭。我们求解了非对称产额Y-和总产额YΣ的耦合玻尔兹曼方程，并确定了标度关系Y-∞∝μ²ε/mφ和ΩDM h²∝mψ μ²ε/mφ，并通过数值验证。观测到的剩余丰度ΩDM h²≈0.12在广泛的参数范围内自然重现；特别是，对于ε=10⁻⁶和mφ=200 GeV，当μ≈2.7×10⁻⁹ GeV和mψ≈40 GeV时，可获得正确的剩余密度。我们进一步将模型与当前的实验约束进行对比，包括直接探测、间接探测、对撞机搜索和暗物质自相互作用，并表明预测信号远低于当前实验的灵敏度。该场景在冻结进入框架内提供了非对称费米子暗物质的一个自洽且可测试的实现。
英文摘要
We present a minimal, predictive scenario for asymmetric fermionic dark matter (DM) generated through freeze-in. The standard model (SM) is extended by a Dirac fermion $ψ$ that serves as the DM candidate, an auxiliary Dirac fermion $χ$, a real scalar mediator $ϕ$, and a heavier real scalar $S$, all stabilized by a $Z_2 \times Z_2'$ discrete symmetry. The DM asymmetry is generated through the CP-violating out-of-equilibrium decays of the mediator $ϕ$, while the heavier scalar $S$ plays a dual role: it generates the physical CP-violating phase required for the asymmetry through its interference with $ϕ$, and it mediates the annihilation of the symmetric component of the DM population. We solve the coupled Boltzmann equations for the asymmetric yield $Y_-$ and the total yield $Y_Σ$, and identify the scaling relations $Y_-^\infty \propto μ^2 \varepsilon / m_ϕ$ and $Ω_{\rm DM} h^2 \propto m_ψ\, μ^2 \varepsilon / m_ϕ$, which we verify numerically. The observed relic abundance $Ω_{\rm DM} h^2 \simeq 0.12$ is naturally reproduced for a wide range of parameters; in particular, for $\varepsilon = 10^{-6}$ and $m_ϕ= 200$~GeV, the correct relic density is obtained for $μ\approx 2.7 \times 10^{-9}$~GeV and $m_ψ\approx 40$~GeV. We further confront the model with current experimental constraints, including direct detection, indirect detection, collider searches, and DM self-interactions, and show that the predicted signals lie far below the sensitivity of current experiments. This scenario provides a self-consistent and testable realization of asymmetric fermionic DM within the freeze-in framework.
