"Figure 13 left" of "Search for long-lived particles decaying to a pair of muons in proton-proton collisions at $\sqrt{s}$ = 13 TeV"

Comparison of the number of events observed in 2016 data in the TMS-TMS dimuon category with the expected number of background events, as a function of the smaller of the two $d_0 / \sigma_{d_0}$ values in the TMS-TMS dimuon. The black points with crosses show the number of observed events; the green and yellow components of the stacked histograms represent the estimated numbers of DY and QCD events, respectively. The last bin includes events in the overflow. The uncertainties in the total expected background (shaded area) are statistical only. Signal contributions expected from simulated $H \rightarrow Z_D Z_D$ with $m_{Z_D}$ of 20 and 50 GeV are shown in red and blue, respectively. Their yields are set to the corresponding combined median expected exclusion limits at 95% CL, scaled up as indicated in the legend to improve visibility.

本研究对比了TMS-TMS双μ子（dimuon）类别中2016年数据的观测事件数与预期本底事件数，该对比以TMS-TMS双μ子系统内两个$d_0/sigma_{d_0}$（$d_0$为轨迹冲击参数，$sigma_{d_0}$为其测量不确定度）值中的较小者作为自变量。带叉的黑色数据点代表观测事件数目；堆叠直方图的绿色与黄色分量分别对应Drell-Yan（DY）与量子色动力学（QCD）过程的预期事件数目。最后一个分箱包含溢出事件。总预期本底的不确定度（阴影区域）仅为统计不确定度。由模拟得到的希格斯玻色子衰变至$Z_D Z_D$（$H
ightarrow Z_D Z_D$）过程的信号贡献，其中$Z_D$的质量$m_{Z_D}$分别为20 GeV与50 GeV，分别以红色与蓝色曲线展示。其产额被设置为对应95%置信度（Confidence Level, CL）下的联合中位数预期排除极限，并按照图例所示进行缩放以提升可视化效果。