"Figure 38 aux" of "Search for long-lived particles using out-of-time trackless jets in proton-proton collisions at $\sqrt{s}$ = 13 TeV"

A search for long-lived particles decaying in the outer regions of the CMS silicon tracker or in the calorimeters is presented. The search is based on a data sample of proton-proton collisions at $\sqrt{s} = 13$ TeV recorded with the CMS detector at the LHC in 2016-2018, corresponding to an integrated luminosity of 138 $\text{fb}^{-1}$. A novel technique, using trackless and out-of-time jet information combined in a deep neural network discriminator, is employed to identify decays of long-lived particles. The results are interpreted in a simplified model of chargino-neutralino production, where the neutralino is the next-to-lightest supersymmetric particle, is long-lived, and decays to a gravitino and either a Higgs or $Z$ boson.This search is most sensitive to neutralino proper decay lengths of approximately 0.5 m, for which masses up to 1.18 TeV are excluded at 95% confidence level. The current search is the best result to date in the mass range from the kinematic limit imposed by the Higgs mass up to 1.8 TeV.本文报道了一项针对在CMS探测器（CMS detector）硅径迹探测器（silicon tracker）外层区域或量能器（calorimeters）中发生衰变的长寿命粒子的搜索分析。该分析依托大型强子对撞机（Large Hadron Collider, LHC）上CMS探测器在2016至2018年间采集的质心系能量√s=13 TeV的质子-质子对撞数据样本，对应积分亮度为138 fb⁻¹。研究采用了一项新颖分析技术：将无径迹喷注与时序偏移喷注的信息进行融合，依托深度神经网络（deep neural network）构建判别器，以识别长寿命粒子的衰变信号。研究结果在一个简化的chargino（chargino）-中性微子（neutralino）产生模型下进行诠释：该模型中中性微子为次轻量级超对称粒子（next-to-lightest supersymmetric particle），属于长寿命粒子，其衰变产物为引力微子（gravitino）以及希格斯玻色子（Higgs boson）或Z玻色子（Z boson）。本次搜索对固有衰变长度约为0.5米的中性微子最为敏感，在此类参数下，质量上限达1.18 TeV的模型参数在95%置信度下被排除。在由希格斯质量限定的运动学极限至1.8 TeV的质量区间内，本次搜索是目前为止的最优实验结果。