Development of the event generator for LHC including higher order corrections

开发大型强子对撞机事件发生器，包括高阶校正

• 批准号: 14340081
• 负责人: SHIMIZU Yoshimitsu
• 金额: $ 5.12万
• 依托单位: High Energy Accelarator Reseach Organization (2004)The High Energy Accelerator Research Organization (2002-2003)
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2004
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14340081/
• 关键词: Perturbative QCD; Higher order corrections; event generator; Automatics system for Feynman diagrams; LHC experiments; soft; collinear approximation; loop correction; Parton shower; collinear近似計算; QCD; NLLパートンシャワー; 自動計算; 多体生成反応; NLO計算; CD; ; Perturbative QCD; Higher order corrections; event generator; Automatics system for Feynman diagrams; LHC experiments; soft; collinear approximation; loop correction; Parton shower; collinear近似計算; QCD; NLLパートンシャワー; 自動計算; 多体生成反応; NLO計算; CD

The LHC(Large Hadron Collider) project at CERN is planned as the next-generation energy-frontier experiment. The LHC accelerator, which is a proton-proton colliding machine with the center-of-mass energy 14 TeV is under construction toward a beam commissioning in 2007. From Japan, more than hundred physicists participate to one of experimental groups (ATLAS collaboration), and are preparing for the coming experiments.One of physics motivations of the LHC experiments is to discover the Higgs particle, which is the only one missing ingredient in the standard model. In order to establish the model completely it is essential to find it and to investigate in details. It should be also important to search for new phenomena beyond the standard model through a tiny deviation of the experimental observations from theoretical predictions. Further not only for searching for new phenomena, but also performing precise measurement of parameters included in the standard model is another important iss … More ue of LHC.The background of the proton-proton colliding experiment must be completely predicted by QCD. This is, however, only 'in principle'. In fact it is very difficult task to make precise predictions because of an inherent feature of QCD. First of all, as QCD has a very large coupling constant, the convergence of perturbation series becomes very poor, or sometimes a perturbative calculation itself is meaningless. Moreover even in the region where the perturbation is applicable, there is no good renormalization point well defined experimentally. Then the lowest level(tree-level) calculation does not have any predictive power for the probability of the event rate. We need both higher-order perturbation and non-perturbative calculations for precise predictions of the background behavior.In this project we have established the method how to construct the event generator that includes the higher-order corrections based on the perturbative QCD. The key ingredients of calculation are as follows;1) Matrix Element I (lowest order),2) Matrix Element II (loop correction),3) Matrix Element III (real radiation),4) Loop Integration,5) Soft/Collinear Approximation,6) Parton-Shower model, 7) Matching between the matrix element and the parton shower.According to the study of above items, some simple examples of event generators (for Drell-Yan and prompt photon processes) have been constructed in this project. Now we are ready to calculate more complex processes like 'WIZ boson + jets'. Less

计划将CERN的LHC（大型强子对撞机）项目作为下一代能量范围实验。 LHC加速器是一台质子 - 质子碰撞机器，与质量中心能量14 TEV正在建造2007年的横梁调试。从日本到日本，成百上万的物理学家参加了一个实验组（ATLAS协作），并正在为即将到来的实验做好准备。仅一位lhc的实验是一个唯一的模型。为了完全建立模型，必须详细研究并进行调查。通过从理论预测的实验观察结果很小的不同之外，搜索超出标准模型的新现象也应该很重要。进一步，不仅要搜索新现象，而且还对标准模型中包含的参数进行精确测量是另一个重要的ISS ...更多的LHC UE。质子 - 蛋白粉碰撞实验的背景必须由QCD完全预测。但是，这仅是“原则上”。实际上，由于QCD的继承功能，进行精确预测是非常困难的。首先，由于QCD具有非常大的耦合常数，因此扰动系列的收敛性变得非常差，或者有时扰动计算本身毫无意义。此外，即使在适用扰动的区域，实验中也没有良好的重归化点。那么最低级别（树级）计算对于事件速率的概率没有任何预测能力。我们需要高阶扰动和非扰动计算，以进行背景行为的精确预测。在本项目中，我们已经建立了如何构造基于扰动QCD的高阶校正的事件生成器的方法。计算的关键诱导如下：1）矩阵元素i（最低顺序），2）矩阵元素II（循环校正），3）矩阵元素III（真实辐射）（实际辐射），4）循环整合，5）软/共线近似，6）6）parton-shower模型，7）parton-shower模型，7）匹配矩阵隔间的典范。该项目已构建了DRELL-YAN和及时的光子过程）。现在，我们准备计算“ Wiz Boson + Jets”之类的更复杂的过程。较少的