Study of New Phenomena by the Collider LEP at CERN

CERN 的 LEP 对撞机研究新现象

基本信息

批准号：
03041087
负责人：
SHIMIZU Yoshimitsu
金额：
$ 4.48万
依托单位：
National Laboratory for High Energy Physics (KEK)
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-03041087/
关键词：
Electron-positron annihilation Standard model in particle physics Radiative corrction in electro-weak theory QCD parton shower Automatic calculation of Feynman amplitude Higgs particle Supersymmetric model 深非弾性散乱 QCDパ-トンシャワ-超対称性粒子自動計

项目摘要

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.

在LEP实验中观察到迅速的光子生产过程。我们已经检查了该过程e^+e^ - *QQGAMMA，包括一环QCD校正。这项研究是使用法国组的日本组使用不同的正则化方法进行的。在LEP实验中，观察到有两个瘦素和两个光子的事件，这被怀疑是一种新现象。通过使用宽限系统，该系统生成Feynman图并为相应过程生成矩阵元素，我们已经计算了Electro-Weak理论中E^+E^ - *ll ^^ - gammagamma的横截面，这些事件是否基于常规的Qed QED QED相互作用。尽管实验信号超过了上述背景期望，但由于实验性的争议，这些信号仍然不确定。使用宽限系统，我们通过高能实验中的三个和四粒子最终状态对过程进行了系统的计算，例如，通过leph，jlc和so的估算，通过研究了实验的估算。完成了QED Parton淋浴的配方，以便为任意基本过程的高阶QED校正的装饰变得可能是可能的。一种用于一环振幅的数值方法也扩展到多环案例。用于多环案例。用于符号操作的新系统，开发了在表达式中的特征，并且在粒子上的构成了粒子，并且在物理上进行了划分。为了有效执行相位空间集成，显示了一种新的数值集成方法。