Grant-in-Aid for Scientific Research (B)
|Allocation Type||Single-year Grants |
|Research Institution||High Energy Accelarator Reseach Organization (2004)|
SHIMIZU Yoshimitsu High Energy Accelarator Reseach Organization, Institute of Particle Nuclear Studies, Professor, 素粒子原子核研究所, 教授 (20011744)
KAWABATA Setuya High Energy Accelarator Reseach Organization, Applied Research Laboratory, Professor, 計算科学センター, 教授 (40152996)
KANEKO Toshiaki High Energy Accelarator Reseach Organization, Applied Research Laboratory, Professor, 計算科学センター, 教授 (40177522)
YUASA Fukuko High Energy Accelarator Reseach Organization, Applied Research Laboratory, A. Professor, 計算科学センター, 助教授 (00203943)
ISHIKAWA Tadashi High Energy Accelarator Reseach Organization, Applied Research Laboratory, A. Professor, 計算科学センター, 助教授 (90184481)
FUJIMOTO Junpei High Energy Accelarator Reseach Organization, Institute of Partide Nuclear Studies, Research Aasociate, 素粒子原子核研究所, 助手 (90202291)
栗原 良将 高エネルギー加速器研究機構, 素粒子原子核研究所, 助手 (50195559)
加藤 潔 工学院大学, 工学部, 教授 (50152707)
黒田 正明 明治学院大学, 法学部, 教授 (00170134)
|Project Period (FY)
2002 – 2004
Completed (Fiscal Year 2004)
|Budget Amount *help
¥8,000,000 (Direct Cost: ¥8,000,000)
Fiscal Year 2004: ¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 2003: ¥2,400,000 (Direct Cost: ¥2,400,000)
Fiscal Year 2002: ¥3,100,000 (Direct Cost: ¥3,100,000)
|Keywords||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 / ファインマン振幅 / Tevatron実験|
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
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