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。AI 中文总结
研究scotogenic模型在HL-LHC上的嵌套消失径迹加位移顶点拓扑，利用双长寿粒子签名探测产生中微子质量的汤川耦合，在基准点可产生约1212个信号事件并覆盖独立搜索未触及的参数区域。
AI 中文摘要
Scotogenic模型通过小的汤川耦合$\u223c\mathcal{O}(10^{-3})$辐射性地产生亚电子伏特的中微子质量，这些耦合也决定了重中性费米子$\Ntwo$的衰变长度；在压缩谱区域，一个独立的、更小的汤川耦合项$\u223c\mathcal{O}(10^{-6})$还使得带电标量$\etapm$成为长寿粒子。我们研究其双惰性双重态变体的压缩谱区域（$\DMcomp = \mHpm - \mNtwo \simeq 200\MeV$），在该区域中，小的汤川耦合项使得带电标量$\etapm$和重中性费米子$\Ntwo$都成为长寿粒子，并在高亮度LHC（HL-LHC）上产生嵌套级联：$\etapm$留下一条消失径迹（DT），衰变为不可见的$\Ntwo$，后者在宏观距离上传播后形成位移双轻子顶点（DV）。两次缓慢飞行组合成4维飞行时间延迟$\dt\sim200$--$800\ps$，可由CMS MIP定时探测器分辨，而DT到DV的位移矢量继承了母粒子的轨迹方向，产生一种没有标准模型对应物的空间反向指向关联。这两个特征预计可将背景抑制到$B\sim10^{-5}$--$10^{-3}$个事件，并且对于任何高达$B\sim10$个事件的背景，发现显著性仍保持$5σ$。在基准点（$\mNtwo=150\GeV$，固有衰变长度$\ctauH=300\mm$，$\ctauN=189\mm$）下，该策略在$3000\ifb$积分亮度下产生$N_s\approx1212$个信号事件，并在$15\mm\lesssim\ctauH\lesssim300\mm$、$10\mm\lesssim\ctauN\lesssim1000\mm$范围内建立灵敏度，这是一个任何独立的DT或DV搜索都未覆盖的关联区域。由于$\Ntwo$的衰变长度由产生亚电子伏特中微子质量的同一汤川耦合控制，绘制这一嵌套级联将HL-LHC转变为对产生中微子质量的相互作用的直接对撞机探针。
英文摘要
The scotogenic model generates sub-eV neutrino masses radiatively through small Yukawa couplings $\sim\mathcal{O}(10^{-3})$ that also set the decay length of the heavy neutral fermion $\Ntwo$; in the compressed regime a separate, much smaller Yukawa entry $\sim\mathcal{O}(10^{-6})$ additionally renders the charged scalar $\etapm$ long-lived. We study the compressed-spectrum regime of its two-inert-doublet variant ($\DMcomp = \mHpm - \mNtwo \simeq 200\MeV$), in which small Yukawa entries render both the charged scalar $\etapm$ and the heavy neutral fermion $\Ntwo$ long-lived and produce a nested cascade at the High-Luminosity LHC~(HL-LHC): $\etapm$ leaves a disappearing track~(DT), decays to an invisible $\Ntwo$, which travels macroscopically before forming a displaced dilepton vertex~(DV). The two slow flights combine into a 4D time-of-flight delay $\dt\sim200$--$800\ps$ resolvable by the CMS MIP Timing Detector, while the DT-to-DV displacement vector inherits the parent track direction, yielding a spatial back-pointing correlation with no SM analogue. These two handles are expected to suppress the background to $B\sim10^{-5}$--$10^{-3}$ events, and the discovery remains $5σ$-significant for any background up to $B\sim10$ events. At the benchmark ($\mNtwo=150\GeV$ and proper decay lengths $\ctauH=300\mm$, $\ctauN=189\mm$) the strategy yields $N_s\approx1212$ signal events at $3000\ifb$ and establishes sensitivity across $15\mm\lesssim\ctauH\lesssim300\mm$, $10\mm\lesssim\ctauN\lesssim1000\mm$, a correlated region left uncovered by any standalone DT or DV search. Because the $\Ntwo$ decay length is controlled by the same Yukawa couplings that generate sub-eV neutrino masses, mapping this nested cascade turns the HL-LHC into a direct collider probe of the interaction responsible for neutrino mass.
Comments11 pages, 4 figures, this paper is accepted for publication in Eur. Phys. J. C
