"Table 2" of "Experimental studies of unbiased gluon jets from e+ e- annihilations using the jet boost algorithm"

CERN-LEP. We present the first experimental results based on the jet boost algorithm, a technique to select unbiased samples of gluon jets in e+e- annihilations, i.e. gluon jets free of biases introduced by event selection or jet finding criteria. Our results are derived from hadronic Z0 decays observed with the OPAL detector at the LEP e+e- collider at CERN. First, we test the boost algorithm through studies with Herwig Monte Carlo events and find that it provides accurate measurements of the charged particle multiplicity distributions of unbiased gluon jets for jet energies larger than about 5 GeV, and of the jet particle energy spectra (fragmentation functions) for jet energies larger than about 14 GeV. Second, we apply the boost algorithm to our data to derive unbiased measurements of the gluon jet multiplicity distribution for energies between about 5 and 18 GeV, and of the gluon jet fragmentation function at 14 and 18 GeV. In conjunction with our earlier results at 40 GeV, we then test QCD calculations for the energy evolution of the distributions, specifically the mean and first two non-trivial normalized factorial moments of the multiplicity distribution, and the fragmentation function. The theoretical results are found to be in global agreement with the data, although the factorial moments are not well described for jet energies below about 14 GeV.

CERN-LEP数据集：本工作基于喷注推进算法（jet boost algorithm）给出首批实验结果，该算法用于在正负电子（e⁺e⁻）湮灭过程中筛选胶子喷注（gluon jets）的无偏样本，即排除事例选择与喷注识别判据引入偏差的纯胶子喷注样本。本研究结果取自欧洲核子研究中心（CERN）LEP正负电子对撞机上OPAL探测器观测到的强子化Z⁰衰变样本。首先，我们通过Herwig蒙特卡洛（Monte Carlo）事例对该喷注推进算法开展验证，结果显示：当喷注能量高于约5 GeV时，该算法可精准测定无偏胶子喷注的带电粒子多重数分布；当喷注能量高于约14 GeV时，则可精准测定喷注粒子能谱（碎裂函数，fragmentation functions）。其次，我们将该喷注推进算法应用于实验数据，得到能量区间约5 GeV至18 GeV内的胶子喷注多重数分布，以及14 GeV与18 GeV处的胶子喷注碎裂函数的无偏测量结果。结合我们此前在40 GeV处的测量结果，我们对上述分布的能量演化开展量子色动力学（QCD，Quantum Chromodynamics）计算验证，具体涵盖多重数分布的均值、前两阶非平庸归一化阶乘矩，以及碎裂函数。尽管当喷注能量低于约14 GeV时，归一化阶乘矩的理论描述与实验数据存在一定偏差，但整体而言理论计算结果与实验数据全局吻合。