1998 Fiscal Year Final Research Report Summary
Parton Showers in Hight Energy Processes
| Project/Area Number |
08640363
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
素粒子・核・宇宙線
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| Research Institution | Yamanashi University |
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Principal Investigator |
MUNEHISA Tomoo Yamanashi University, Fac.of Engr.Assistant Prof., 工学部, 助教授 (30174254)
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| Project Period (FY) |
1996 – 1998
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| Keywords | Hight energy process / parton showers / QED / QCD / NLL approximation / renormalization group equation |
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| Research Abstract |
Event generators, which are indispensable tools to high energy experiments, need showers for producing photons or cartons, based on the renormalization group equation in QED and QCD.The primary purpose of our research is to apply the NLL shower that is improved on accuracy of models to many processes. The target of this research project is (1) making a model in the two photon process, (2) making a NLL model in the e^+e^- annihilation and (3) making a NLL model in the proton.-proton scattering.
The first purpose in the two photon process of the e^+e^- scattering has been accomplished completely, then the paper and the manual has been published. The second one has been achieved almost, which is to make the NLL shower and the event generator including it in the radiative process in the e^+e^- annihilation. Features in the research are precise discussions on delails of the algorithm, because the NLL order is of order of the coupling constant squared of QED, i.e. 10^<-5>. These discussions led to clarifying the accuracy of the shower algorithm in the LL order, which was summarized in a published paper. Furthermore the precise discussions teached us that two fundamental effects were quite important. They are a dynamical change of the coupling and the consistent treatment of the infrared singularity in the NLL order. This progress has enabled us to make the NLL shower and careful tests of the model are going now. A paper has been already written and is included in the research report.
The third purpose has not been completed yet, but extensive study was made for this. Especially it is found that one should use the energy conservation for normalizations of events in treatments of gluons showers, which was discussed in published paper.
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