2002 Fiscal Year Final Research Report Summary
Phenomenological Research on Physics beyond the Standard Model using Photon-Photon Colliders
| Project/Area Number |
11640262
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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 | OCHANOMIZU UNIVERSITY |
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Principal Investigator |
SUGAMOTO Akio Ochanomizu U., Faculty of Science, Professor, 理学部, 教授 (70132686)
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| Co-Investigator(Kenkyū-buntansha) |
WATANABE Isamu Akita Keizaihouka U., Faculty of Economics, Associate Professor, 経済学部, 助教授 (30310163)
GI-CHOL Cho Ochanomizu U., Faculty of Science, Associate Professor, 理学部, 助教授 (10323859)
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| Project Period (FY) |
1999 – 2002
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| Keywords | photon-photon colleder / Higgs particle / Physics beyond the Standard Model / muon colliders / helically amplimode / interference effect |
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| Research Abstract |
The most important topics for the photon-photon collider is the study on the "Higgs particles".
In this research we have given a method to identify heavy neutral Higgs particles in the models having more than two Higgs doublets. For example, in the "Minimal Supersymmetric Standard Model (MSSM)" there are two (heavy and light) CP-even neutral Higgs particles, and there is one CP-odd neutral Higgs particle. Among them the heavier Higgs particle (H) with even CP eigenvalue and the Higgs particle (A) with odd CP eigenvalue usually have almost degenerate masses, and so they are produced in the photo-photon colliders in a mixed manner. The amplitudes of H or A decaying to at (top quark) pair interfer largely with the amplitude describing a fermion pair production without passing through the Higgs particles, and the corresponding cross section depends sensitively on the properties of masses and decay widths etc. of the Higgs particles. Since the top quark is short-lived and its helicity state can be identified, the decay amplitudes of H and A to a top quark pair are shown to be interferred under the proper choice of top quarks' helicities. These cross sections including the interference effects largely are sensitive to the properties of Higgs particles, so that the parameters for H and A are shown to be measured separately. In the muon colliders these interference effects in Higgs particles' production can be also observed Here, the amplitude describing the process without passing through the Higgs particles can be neglected. The amplitudes in the muon colliders in the lowest order do not include the loop effects and are free from the "physics beyond the standard model". Therefore, the ambiguity of the new physics existing in the photon-photon colliders can be extracted by the experiments of the muon colliders. In this sence, the two types of colliders are supplementary with each other. This is the main result of our research.
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