1993 Fiscal Year Final Research Report Summary
Dynamical Symmetry Breaking and Grand Unified Theoreis
| Project/Area Number |
04640292
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
核・宇宙線・素粒子
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
KUGO Taichi Kyoto University, Phys.Dept., Professor, 理学部, 教授 (00115833)
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| Project Period (FY) |
1992 – 1993
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| Keywords | Grand Unified Theory / Effective Potential / Schwinger-Dyson equation / Bethe-Salpeter equation / Renormalization Group equation / Decoupling theorem / Isgur-Wise function |
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| Research Abstract |
The research results of our project for two years in 1992 - 1993 are as follows :
1. We studied in the minimal supersymmetric standard model by using renormalization group equation whether it is possible to explain the large mass ratio between top and bottom quarks under the boundary condition suggested by SO(10) and E_6 grand unified theories. We showed that it can be realized by a combined effect of QCD strong interaction and the SU(2)_R violation owing to U(1)-hypercharge and gamma-lepton.
2. We presented a new general method for obtaining effective potential so as to satisfy the renormal-ization group equation. This method, combined with decoupling theorem, is made applicable to any general system possessing many mass scales.
3. It is pointed out that the Schwinger-Dyson and Bethe-Salpeter equations have to have mutual con-sistencies if they satisfy external gauge invariance. We presented a systematic method for satisfying this gauge invariance at any order of approximation.
4. Applying the improved ladder approximation for BS equation to heavy quark mesons, we calculated the Isgur-Wise function - a universal form factor. Our calculation predicts a few percent larger CKM matrix element V_<cb> than the other calculations.
5. We studied an E_6 grand unified model of a single generation fermion which contains strong 4-fermi interactions. We found that the E_6 symmetry breaks down either to F_4 or to S_p(8) or G_2 or SU(3), depending on the strength relation of the two 4-fermi interactions.
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