"Figure 25 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紧凑型缪子线圈探测器（CMS）硅径迹仪外围区域或量能器中发生衰变的长寿命粒子的搜寻研究。本次搜寻基于2016至2018年大型强子对撞机（Large Hadron Collider，LHC）上CMS探测器采集的质子-质子碰撞数据样本，质心系能量为√s = 13 TeV，积分亮度达138 fb⁻¹。研究采用了一项创新技术：将无径迹喷注与时序外喷注信息相结合，输入深度神经网络判别器，以识别长寿命粒子的衰变信号。研究结果在一个简化的带电伴子（chargino）-中性伴子（neutralino）产生模型中进行诠释，该模型中中性伴子（neutralino）为次轻超对称粒子，寿命较长，且会衰变为引力微子（gravitino）与希格斯玻色子或Z玻色子。本次搜寻对固有衰变长度约为0.5米的中性伴子具有最高灵敏度，在此范围内，质量上限在95%置信度下被排除至1.18 TeV。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，本次搜寻是迄今最优的实验结果。