AI 中文总结
该研究提出用逐个喷注的能量关联子协方差，分析Pythia与Herwig中部分子到强子跃迁的特性，发现强子级协方差更小、相邻壳关联更大，且不同发生器间变化特征存在差异。
AI 中文摘要
能量-能量关联子通常以系综平均形式呈现，因此无法说明不同角区域如何在逐个喷注间共同涨落。我们保留每个喷注的分箱两点关联子，研究其角壳权重的分布与协方差。在高统计量的Pythia样本中，壳变量稀疏且呈强非高斯性，其协方差包含跨多个模式的非零跨壳结构。将每个壳对5个喷注级汇总量进行回归，可保留84%-92%的协方差迹；而壳级置换和组分角打乱无法复现观测到的非对角关联。我们随后对比Pythia和Herwig中分别生成的部分子级与强子级样本，在24种发生器-半径-动量配置下，强子级协方差迹更小，且0.30≤r/R<1范围内的平均相邻壳关联更大。这种变化的大小与角依赖性在不同发生器间存在差异，特征位置分析未识别出共同标度。因此，逐个喷注的EEC协方差提供了平均谱中缺失的、关于部分子到强子跃迁的信息。
英文摘要
Energy-energy correlators are usually reported as ensemble averages and therefore do not specify how different angular regions fluctuate together from jet to jet. We retain the binned two-point correlator for each jet and study the distribution and covariance of its angular-shell weights. In a high-statistics Pythia sample, the shell variables are sparse and strongly non-Gaussian, and their covariance contains nonzero cross-shell structure spread over many modes. Regressing each shell on five jet-level summaries leaves 84-92% of the covariance trace, while shell-wise permutation and constituent-angle shuffling do not reproduce the observed off-diagonal correlations. We then compare separately generated parton- and hadron-level samples in Pythia and Herwig. Across 24 generator-radius-momentum configurations, the hadron-level covariance trace is smaller and the average neighboring-shell correlation over 0.30 <= r/R < 1 is larger. The size and angular dependence of the change differ between the generators, and a characteristic-position analysis does not identify a common scale. Jet-by-jet EEC covariance thus provides information on the parton-to-hadron transition that is absent from the mean spectrum.
Comments14 pages, 11 figures, 2 tables
