2001 Fiscal Year Final Research Report Summary
Research for the origin of generation of elementary particles based on supersymmetric grand unified theory
| Project/Area Number |
11640282
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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 | KYUSHU UNIVERSITY |
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Principal Investigator |
INOUE Kenzo Faculty of Sciences, Kyushu University Prof., 理学研究院, 教授 (90127978)
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| Project Period (FY) |
1999 – 2001
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| Keywords | horizontal symmetry / supersymmetry / grand unified theory / infinite dimensional representation / Yukawa interaction / hierarchy structure / generation of elementary particles / neutrino mass |
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| Research Abstract |
The purpose of this research is to clarify the phenomenological feature of the supersymmetric grand unified theory containing quarks, leptons and Higgses as the infinite dimensional representation of noncompact horizontal symmetry, and search for its theoretical background. The big subject of the grand unified theory is to clarify the mechanism which naturally realizes light Higgs with mass much lighter than unification scale. In this theory, Higgs is realized to be light through phase structure of the theory by the correlation of the spontaneous breakdown of grand unified symmetry and horizontal symmetry. That is, color triplet, which is the GUT partner of Higgs, can obtain huge mass without fine tuning retaining Higgs doublet light. For this, there must be spontaneous symmetry breaking due to two fields which belong to the same SU(1,1) representation but different SU(5) representations. The ratio r of the vacuum expectation values of these two fields determins the chiral particle spectrum of the theory as the phase structure. In order only for the Higgs doublet to be realized chirally, this ratio r must be less than 1. Furthermore, this ratio r reproduces the hierarchical structure in power of r in the Yukawa coupling matrix of quarks and leptons with Higgs. The numerical factor determined by SU(1,1) remarkably enlarges, through diagonalization, the hierarchy of eigenvalues (masses). The big problems of two types of Hierarchies of grand unified theory are understood in a unified manner through spontaneous breakdown of horizontal symmetry. In this theory, neutrinos acquire masses through mechanism different from well-known seesaw mechanism. The largest element is off-diagonal 2-3 generation element, and therefore the maximal mixing between mu-nutrino and tau-nutrino is realized.
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