The first measurement of two-particle angular correlations for charged particles with LEP-II data is presented. The study is performed using archived hadronic data collected by ALEPH at center-of-mass energies up to 209 GeV, above the production threshold, which provide access to unprecedented charged-particle multiplicities and more complex color-string configurations if compared to previous measurements at LEP-I energies. An intriguing long-range near-side excess is observed in the correlation function measured with respect to the thrust axis in the highest multiplicity interval (). Such a structure is not predicted by the Monte-Carlo simulation. The harmonic anisotropy coefficients , which result from the Fourier expansion of the two-particle correlation functions, were also measured for the first time in data, and compared to 6 predictions and to the results obtained in proton-proton collisions. The results presented in the Letter provide novel experimental constraints on the formation of collective phenomena in point-like collisions.

中文翻译：

---

183-209 GeV e+e− 碰撞中与 ALEPH 存档数据的长程近侧关联


首次使用 LEP-II 数据测量带电粒子的双粒子角相关性。这项研究是使用 ALEPH 收集的存档强子数据进行的，质心能量高达 209 GeV，高于生产阈值，与之前在LEP-I 能量。在相对于最高重数区间 () 中的推力轴测量的相关函数中观察到一个有趣的远程近侧过量。蒙特卡罗模拟无法预测这种结构。调和各向异性系数 是由两粒子相关函数的傅里叶展开产生的，也首次在数据中进行了测量，并与 6 个预测以及质子-质子碰撞中获得的结果进行了比较。信中提出的结果为点状碰撞中集体现象的形成提供了新颖的实验约束。