标题： 极化和多强子Z0衰变中的自旋 alignments 显示英文标题

标题： Polarization and Spin Alignment in Multihadronic Z0 Decays

摘要： 数百万次强子Z0衰变的大统计量，由四个LEP实验在1989年至1995年间积累，使得对碎裂过程的详细研究成为可能。 在中间和高动量下发现包含Lambda_b重子和Lambda超子表现出纵向极化。 这可能与初级夸克和反夸克的极化以及产生领先重子的强子化机制有关。 对于各种矢量介子，在非包容性产生的强子Z0衰变中测量了自旋密度矩阵元。 一些轻介子和D*+-的对角元素如果介子携带了可用能量的较大份额，则显示出对零自旋态的偏好。 这种自旋排列在初级部分子向矢量介子的非微扰强子化过程中产生的机制目前尚无解释。 对于B*，结果与没有自旋排列一致，这在基于HQET的图像中是可以预期的。 对于某些介子种类，已经测量了非对角元素，表明由于初级夸克和反夸克之间的最终状态相互作用导致的相干现象。 显示英文摘要

摘要： The large statistics of millions of hadronic Z0 decays, accumulated by the four LEP experiments between 1989 and 1995, allowed for detailed investigations of the fragmentation process. Inclusive Lambda_b baryons and Lambda hyperons at intermediate and high momentum have been found to show longitudinal polarization. This may be related to the primary quark and antiquark polarization and the hadronization mechanism which produces the leading baryons. Helicity density-matrix elements have been measured for a variety of vector mesons produced inclusively in hadronic Z0 decays. The diagonal elements of some of the light mesons and the D*+- show a preference for a helicity-zero state if the meson carries a large fraction of the available energy. The mechanism which produces such spin alignment in the non-perturbative hadronization of the primary partons to the vector mesons is so far unexplained. For the B* the results are consistent with no spin alignment, which is expected in a picture based on HQET. For some meson species non-diagonal elements have been measured indicating coherence phenomena due to final-state interaction between the primary quark and antiquark.