在高亮度大型强子对撞机（HL-LHC）上通过四维时空追踪探测超压缩 Scotogenic 暗物质
Probing Ultra-Compressed Scotogenic Dark Matter at the HL-LHC via 4D Spacetime Tracking
浏览论文内容
中文总结 AI 辅助
本研究提出利用 HL-LHC 的四维时空追踪策略，针对超压缩 Scotogenic 暗物质实现零背景探测，可将带电惰性标量质量排除至约 670 GeV，为传统难以探测的共湮灭区域提供了新方法。
中文摘要 AI 辅助
超压缩 Scotogenic regime 中，带电惰性标量与暗物质费米子之间存在 2 GeV 的质量分裂，该分裂由剩余模型参数的合适选择所驱动，且与共湮灭产生观测到的遗迹密度相兼容，这种机制会产生衰变轻子，而现有的 LHC displaced 轻子和消失径迹搜索仅保留了部分、未优化的接受度，为专门的计时辅助策略留下了空间。我们提议利用 HL-LHC 精密计时探测器 30 ps 的计时分辨率作为第四种可观测量，将标量的宏观衰变长度 100–1000 mm 转化为 70–700 ps 的到达时间延迟，该延迟比所有 prompt 标准模型（SM）背景的亚皮秒延迟高出三个数量级以上。我们的四维计时策略在低横动量（low-$p_T$）消失径迹 stub 匹配延迟计时命中的层面运行，无需完整轻子重建，在探测的质量范围内实现了 12–36% 的信号效率（200 GeV 基准点处为 14%），在 $4.20\times10^6$ 个模拟 prompt SM 事件中实现了零背景，在保守背景假设下，于 3000 fb$^{-1}$ 的积分亮度下，可将标量质量排除至约 670 GeV（置信水平 95%）。标量寿命由 Yukawa 耦合 $y$ 决定，满足 $c\tau\backsim y^{-2}$，而亚电子伏特的中微子质量仅约束乘积 $y^2\backslash lambda_5$；因此，使带电标量处于最优计时窗口的小耦合与辐射中微子质量机制相兼容（但并非由其唯一确定），这使得共湮灭 corridor——传统上最难以探测的 regime——成为 HL-LHC 四维时空追踪的可及目标。
英文摘要
The ultra-compressed scotogenic regime, in which a 2\,GeV mass splitting between the charged inert scalar and the dark-matter fermion is motivated by and compatible with co-annihilation to the observed relic density for suitable choices of the remaining model parameters, produces decay leptons for which existing LHC displaced-lepton and disappearing-track searches retain only partial, unoptimised acceptance, leaving room for a dedicated timing-assisted strategy. We propose exploiting the 30\,ps timing resolution of the HL-LHC precision timing detectors as a fourth observable, converting the macroscopic scalar decay length of 100--1000\,mm into an arrival-time delay of 70--700\,ps---more than three orders of magnitude above the sub-picosecond delays of all prompt Standard Model backgrounds. Operating at the level of a low-$p_T$ disappearing-track stub matched to a delayed timing hit, without requiring full lepton reconstruction, our 4D timing strategy achieves signal efficiencies of 12--36\% across the probed mass range (14\% at the 200\,GeV benchmark) and zero background across $4.20\times10^6$ simulated prompt SM events, projecting 95\%\,C.L.\ exclusion up to scalar masses of $\simeq\!670$\,GeV at 3000\,fb$^{-1}$ under conservative background assumptions. The scalar lifetime is set by the Yukawa coupling $y$ through $cτ\propto y^{-2}$, while sub-eV neutrino masses constrain only the product $y^2λ_5$; the small couplings that place the charged scalar in the optimal timing window are therefore compatible with, though not uniquely fixed by, the radiative neutrino-mass mechanism, making the co-annihilation corridor---conventionally the most elusive regime---an accessible target for 4D spacetime tracking at the HL-LHC.
发表机构
- Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所）
机构由 AI 辅助整理，请以论文原文为准。
