| Project/Area Number |
08044089
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Joint Research |
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| Research Field |
素粒子・核・宇宙線
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| Research Institution | HIROSSHIMA UNIVERSITY |
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Principal Investigator |
MUTA Taizo Hiroshima University, department of Physics, Professor, 理学部, 教授 (80025353)
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| Co-Investigator(Kenkyū-buntansha) |
ONOGI Tetsuya Hiroshima University,Research Associate, 理学部, 助手 (70211802)
KODAIRA Jiro Hiroshima University,Associate Professor, 理学部, 助教授 (40127080)
MOROZUMI Takuya Hiroshima University,Lecturer, 理学部, 講師 (20253049)
LIM Seiji Kobe University, Professor, 理学部, 教授 (80201870)
REBELO M. N. リスボン工科大学, 物理学科, 助教授
BRANCO G. C. リスボン工科大学, 物理学科, 正教授
TANIMOTO Morimitsu Ehime University, Professor, 理学部, 教授 (90108366)
M.N Rebolo AvRovisco Paris, Professor
G.C Branco AvRovisco Paris, Professor
REBELO M.N. リスボン工科大学, 物理学科, 助教授
BRANCO G.C. リスボン工科大学, 物理学科, 正教授
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| Project Period (FY) |
1996 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥7,500,000 (Direct Cost: ¥7,500,000)
Fiscal Year 1997: ¥4,600,000 (Direct Cost: ¥4,600,000)
Fiscal Year 1996: ¥2,900,000 (Direct Cost: ¥2,900,000)
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| Keywords | Quark / Lepton / Origin of mass / CP violation / B meson / Dynamical symmetry breaking / クオーク質量 / フレーバー混合 / シ-ソ-機構 / CPの破れ / トップクオーク / FCNC / 小林、益川角 |
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| Research Abstract |
The standard theory of elementary particles seems to have been established after a number of serious experimental confrontations. It is, however, not within the reach of the standard theory to explain the mechanism of generating the quark and lepton masses and the origin of the CP violation. The purpose of our research project is to explore models of elementary particles lying behind the standard theory and to propose experimental means to test these models. For this purpose we settled the following two research subjects: (1) Clarifying the mechanism of the generation of quark masses, (2) understanding the origin of the CP violation.
(1) Mechanism of the generation of quark masses
In order to understand the mechanism of the mass generation on the basis of quantum field theory we have studied the dynamical breaking of the chiral symmetry at finite temperature as well as under the strong external gravity by the use of nonperturbative methods, and have clarified the dynamical mechanism of g
… More
enerating masses in the analytical approach. With this analysis we got an insight into a clue to investigate the process how the quark and lepton masses are generated in the early stage of the Universe.
In the standard theory we are not able to find an answer to the question why the top quark mass is of the order of the electro weak mass scale (100-200 GeV) and the masses of the other quarks and leptons are much smaller than the top quark mass. In the present research we attempted to answer the Question in the framework of the left-right symmetric mode. The model is suited to explain the light quark and lepton masses as the see-saw mechanism is built in. After the discovery of the top quark which is much heavier than the present study it is found that the see-saw mechanism may be adjusted to make no influence to the top quark keeping the top quark mass of the order of the electro weak mass scale. Accordingly the left-right symmetric model is found to be worth consideration for a candidate of the model behind the standard theory.
(2) Origin of the CP violation
We examined how the Kobayashi-Maskawa matrix is derived in the left-right symmetric model. Unlike to the standard theory the model exhibits the violation of the unitarily of the Kobayashi-Maskawa matrix. As a result the neutral current shows up at the tree level. The size of the neutral current is estimated to be sufficiently small so that it is well below the present experimental bound. However experimental tests in the B factory which will be soon operating are found to be quite hard. It will be our future task to extend the present analysis to that of the K meson system and the neutrino physics. Less
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