"Table 7" of "Measurements of observables sensitive to colour reconnection in $t\bar{t}$ events with the ATLAS detector at $\sqrt{s}=13$ TeV"

- CERN-LHC. A measurement of observables sensitive to effects of colour reconnection in top-quark pair-production events is presented using $139~\text{fb}^{-1}$ of 13 TeV proton--proton collision data collected by the ATLAS detector at the LHC. Events are selected by requiring exactly one isolated electron and one isolated muon with opposite charge and two or three jets, where exactly two jets are required to be $b$-tagged. For the selected events, measurements are presented for the charged-particle multiplicity, the scalar sum of the transverse momenta of the charged particles, and the same scalar sum in bins of charged-particle multiplicity. These observables are unfolded to the stable-particle level, thereby correcting for migration effects due to finite detector resolution, acceptance and efficiency effects. The particle-level measurements are compared with different colour reconnection models in Monte Carlo generators. These measurements disfavour some of the colour reconnection models and provide inputs to future optimisation of the parameters in Monte Carlo generators.

欧洲核子研究中心（CERN）大型强子对撞机（LHC）上的ATLAS探测器（ATLAS detector），利用其采集的139 fb⁻¹、质心系能量13 TeV的质子-质子碰撞数据集，报告了顶夸克对产生事件中对色重联（colour reconnection）效应敏感的可观测物理量的测量结果。实验通过以下筛选条件选取事件：要求恰好一个孤立电子、一个电荷相反的孤立缪子，以及2或3个喷注，且其中恰好2个喷注需经b标记（b-tagged）。针对筛选得到的事件，本文给出了带电粒子多重数、带电粒子横向动量标量和，以及按带电粒子多重数分箱后的该标量和的测量结果。上述可观测物理量被展开至稳定粒子层面，以此校正由有限探测器分辨率、接收度及探测效率所引发的迁移效应。随后将粒子层面的测量结果与蒙特卡洛模拟程序（Monte Carlo generator）中的不同色重联模型进行比对。本次测量结果不支持部分色重联模型，并可为未来蒙特卡洛模拟程序的参数优化提供输入依据。