AI 中文总结
本研究在幺正引力框架下探究能量扩散标量场驱动的非标准宇宙学情形，发现其可重塑WIMP暗物质的允许参数空间，打开$\Lambda$CDM中被排除的区域，并改变实单态标量WIMP模型的未来探测前景。
AI 中文摘要
我们研究了幺正引力（Unimodular Gravity，UG）框架下的一种非标准宇宙学（non-standard cosmology，NSC）情形，该情形由经历能量扩散的标量场$\phi$驱动，其参数包括扩散参数$x$、初始能量密度比$\kappa\equiv\rho_\phi/\rho_\gamma|_{\text{ini}}$以及主导结束温度$T_{\text{end}}$。我们将这种UG+NSC情形与标准非标准宇宙学、$\Lambda$CDM宇宙学中通过退耦机制产生的大质量弱相互作用粒子（WIMP）暗物质（Dark Matter，DM）进行了对比。我们发现能量扩散重塑了允许的$(m_\chi, \langle\sigma v\rangle)$参数空间，其中$m_\chi$为暗物质质量，$\langle \sigma v \rangle$为热平均湮灭截面；该过程打开了在$\Lambda$CDM模型中因暗物质过量产生而被排除的区域，并且会根据$x$、$\kappa$、$T_{\text{end}}$以及$\phi$的正压指数$\omega$，改变WIMP候选体可及的质量与截面范围。作为具体应用，我们将该框架应用于实单态标量WIMP，结合LZ实验当前的直接探测限制检验其$(m_\chi, \lambda_{HS})$参数空间，结果表明能量扩散打开了希格斯门户耦合$\lambda_{HS}$中此前未受约束的区域，从而改变了该基准模型在未来探测中的可观测前景。
英文摘要
We study a non-standard cosmology (NSC) scenario within the Unimodular Gravity (UG) framework, sourced by a scalar field $ϕ$ that undergoes energy diffusion, parametrized by the diffusion parameter $x$, the initial energy densities rate $κ\equivρ_ϕ/ρ_γ|_{\text{ini}}$, and the end-of-domination temperature $T_{\text{end}}$. We compare this UG+NSC scenario with standard NSC and $Λ$CDM cosmologies for WIMP Dark Matter (DM) production via the freeze-out mechanism. We find that energy diffusion reshapes the allowed $(m_χ, \langleσv\rangle)$ parameter space, where $m_χ$ is the DM mass and $\langle σv \rangle$ is the thermally averaged annihilation cross section, opening regions otherwise excluded by DM overproduction in $Λ$CDM, and shifting the mass and cross-section ranges accessible to WIMP candidates depending on $x$, $κ$, $T_{\text{end}}$, and the barotropic index $ω$ of $ϕ$. As a concrete application, we implement this framework for the Real Singlet Scalar WIMP and test its $(m_χ, λ_{HS})$ parameter space against current direct detection bounds from the LZ experiment, showing that energy diffusion opens previously unconstrained regions in the Higgs-portal coupling $λ_{HS}$ and thereby alters the detectability prospects of this benchmark model in future searches.
Comments15 pages, 16 figures
