"Table 105" of "Properties of jet fragmentation using charged particles measured with the ATLAS detector in $pp$ collisions at $\sqrt{s}=13$ TeV"

CERN-LHC. This paper presents a measurement of quantities related to the formation of jets from high energy quarks and gluons (fragmentation). Jets with $100$ GeV $ 500$ MeV~and $|\eta| < 2.5$~are used to probe the detailed structure of the jet. The fragmentation properties of the more forward and the more central of the leading two jets from each event are studied. The data are unfolded to correct for detector resolution and acceptance effects. Comparisons to parton shower Monte Carlo generators indicate that existing models provide a reasonable description of the data across a wide range of phase space, but there are also significant differences. Furthermore, the data are interpreted in the context of quark- and gluon-initiated jets by exploiting the rapidity dependence of the jet flavor fraction. A first measurement of the charged-particle multiplicity using model-independent jet labels (topic modeling) provides a promising alternative to traditional quark- and gluon- extractions using simulation input. The simulations provide a reasonable description of the quark-like data across the jet $p_\text{T}$ range presented in this measurement, but the gluon-like data have systematically fewer charged particles than the simulations. Uncertainties are broken down by category and should be treated as fully correlated between bins and between observables except for statistical uncertainties.

本研究依托欧洲核子研究中心大型强子对撞机（CERN-LHC）完成。本文针对高能夸克与胶子喷注（jet）的喷注碎裂过程（fragmentation）相关物理量开展测量。选取横向动量满足100 GeV < (p_ ext{T}) < 500 GeV、带电粒子横向动量(p_ ext{T}^ ext{ch}) > 500 MeV且赝快度(|eta| < 2.5)的喷注，用于探究喷注的精细结构。本研究针对每个事件中前两领头喷注里更靠近前向与更中心的两类喷注的碎裂特性展开分析。对实验数据进行解卷（unfold）处理，以校正探测器分辨与接收度效应带来的系统偏差。通过与部分子簇射（parton shower）蒙特卡洛发生器的比对结果表明，现有模型可在较宽相空间范围内对实验数据给出合理描述，但二者间仍存在显著差异。此外，本研究借助喷注味组分的快度依赖关系，将实验数据按夸克初始喷注与胶子初始喷注两类场景进行阐释。首次采用与模型无关的喷注标签（主题建模，topic modeling）方法测量带电粒子多重数，为替代传统依赖模拟输入的夸克与胶子喷注甄别手段提供了极具前景的新思路。蒙特卡洛模拟可在本次测量覆盖的喷注横向动量区间内对类夸克数据给出合理描述，但类胶子数据的带电粒子多重数系统性低于模拟结果。不确定度按类别拆分，除统计不确定度外，各分箱（bin）间与各观测量间的不确定度均视为完全相关。