发表机构
University of Utah; The University of Texas at Austin（犹他大学; 德克萨斯大学奥斯汀分校）
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WIMP与可衰变的重伙伴粒子耦合的扩展模型，通过求解玻尔兹曼方程发现伙伴粒子衰变可显著增强WIMP湮灭截面（最高达三个数量级），并可由间接探测实验检验，NMSSM可实现该情景。
AI 中文摘要
弱相互作用大质量粒子（WIMP）构成了最有力的暗物质（DM）候选者之一。在本研究中，我们考虑了WIMP范式的一种简单扩展，其中WIMP与一个更重的粒子耦合，该粒子仅与WIMP相互作用，并且可以衰变为WIMP。在早期宇宙中，当WIMP与标准模型（SM）热浴处于热平衡时，它们充当一个门户，通过逆衰变来填充重伙伴粒子。取决于伙伴粒子的寿命，其最终衰变为WIMP可以显著改变WIMP的丰度。如果伙伴粒子在WIMP从平衡中冻结之前衰变为WIMP，则标准的热历史保持不变。然而，当衰变发生在WIMP冻结之后时，注入的非热WIMP群体可能导致暗物质过产生，因此需要相对于没有伙伴粒子的标准情景更大的WIMP湮灭截面。对于给定的伙伴粒子寿命和WIMP湮灭截面，冻结可能由于重新湮灭而延迟，或者随后进入冻结-入阶段。通过半解析和数值求解玻尔兹曼方程，我们探索了这些热历史，并研究了相对于标准值所需的WIMP湮灭截面的增强。这种增强可以达到三个数量级，导致晚期宇宙中更强的湮灭信号。因此，当前和即将进行的间接探测实验能够探测伙伴粒子的寿命。我们简要探讨了我们的情景与宇宙重子不对称性之间可能的联系。作为例子，我们展示了次最小超对称标准模型（NMSSM）可以提供我们情景的实现，并有可能容纳具有正确遗迹丰度的轻higgsino暗物质。
英文摘要
Weakly interacting massive particles (WIMPs) constitute one of the best-motivated dark matter (DM) candidates. In this study, we consider a simple extension of the WIMP paradigm in which WIMPs are coupled to a heavier particle that interacts only with them and can decay into WIMPs. In the early Universe, when WIMPs are in thermal equilibrium with the Standard Model (SM) bath, they serve as a portal to populate the heavy partner through inverse decays. Depending on the lifetime of the partner particle, its eventual decay into WIMPs can significantly alter the WIMP abundance. If the partner decays into WIMPs before their freeze-out from equilibrium, the standard thermal history remains unchanged. When the decay occurs after WIMP freeze-out, however, the injected non-thermal population of WIMPs can result in an overproduction of DM, therefore requiring a larger WIMP annihilation cross section relative to the standard scenario without the partner. For a given partner lifetime and WIMP annihilation cross section, freeze-out may be delayed due to re-annihilation or followed by a freeze-in phase. By solving the Boltzmann equations both semi-analytically and numerically, we explore these thermal histories and study the required enhancement in the WIMP annihilation cross section compared to the canonical value. This enhancement, which can reach up to three orders of magnitude, leads to stronger annihilation signals in the late Universe. As a result, current and upcoming indirect detection experiments are able to probe the lifetime of the partner particle. We briefly explore possible connections between our scenario and the baryon asymmetry of the Universe. As an example, we show that the Next-to-Minimal Supersymmetric Standard Model (NMSSM) can provide a realization of our scenario, with the possibility of accommodating light higgsino DM with the correct relic abundance.
Comments20 pages, 5 figures
