Study of New Phenomena by the Collider LEP at CERN

在LEP实验中观察到了快速的光子产生过程。我们研究了包含单圈QCD校正的过程e^+e^-*qqGamma。这项研究是由法国GROUP的日本小组用不同的正则化方法完成的。在LEP实验中，观察到了两个轻子和两个光子的事件，这可能是一个新的现象。利用GRACE系统生成Feynman图和相应过程的矩阵元，我们计算了电弱理论中e^+e^-*ll^-伽玛的截面，无论这些事件是基于高阶QED相互作用的常规事件。虽然实验信号超出了上述背景的预期，但由于实验上的争议，这些信号的来源仍然不确定。我们利用GRACE系统，对高能e^+e^-实验中的三粒子和四粒子末态过程，如LEPH，JLC等进行了系统的计算。通过研究部分子簇射模型NLLJET的实验数据和包括恢复在内的解析计算，估计了强耦合常数。完成了QED部分子簇射的公式推导，因此，对任意基本过程的高阶QED修正成为可能。单圈振幅的数值方法也扩展到多圈情况。发展了一个新的符号处理系统，它具有压缩粒子物理计算中出现的表达式的特点。研究了包括超粒子产生在内的一些过程，展示了未来对撞机可能期望的信号。为了有效地执行相空间积分，研究了一种新的数值积分方法。

The prompt photon production process is observed in LEP experiments. We have examined the process e^+e^-*qqgamma including one-loop QCD correction. This research is done using different regularization method by Japanese group by French group.In LEP experiments, events with two leptons and two photons are observed, which are suspected to be a new phenomenon. By use of GRACE system, the system to generate Feynman diagrams and to generate matrix elements for a corresponding process,we have calculated the cross section for e^+e^-*ll^^-gammagamma in electro-weak theory, whether the events are conventional ones based on the higher order QED interaction. Though the experimental signal exceeds the above background expectations, the origin of these is still uncertain due to the experimental controversy.Using the GRACE system, we have done systematic computation of the processes with three- and four-particle final states in high energy e^+e^- experiments, e.g., LEPH, JLC and so forth.The estimation of the strong coupling constant is done by studying experimental data by the parton shower model NLLjet and by the analytic calculation including resummation.The formulation of QED parton shower is done, so that the decoration of higher order QED correction for an arbitrary elementary process becomes possible.The numerical method developed for one-loop amplitude is also extended to multi-loop case.A new system for the symbolic manipulation is developed It has the feature to contract the expressions which appear in the calculation in particle physics.Some processes including the production of the super-particles are studied and the possible signal expected in the future colliders is shown.To execute the phase space integration efficiently, a new method for the numerical integration is investigated.