| Project/Area Number |
08640365
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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 | Nagoya University |
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Principal Investigator |
YAMAWAKI Koichi Nagoya University, Graduate Course of Particle and Astrophysical Science, Professor, 大学院・理学研究科, 教授 (90135301)
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| Co-Investigator(Kenkyū-buntansha) |
TANABASHI Masaharu Tohoku University, Graduate School of Science, Associate Professor, 大学院・理学研究科, 助教授 (00270398)
NISHIMURA Jun Nagoya University, Graduate Course of Particle and Astrophysical Science, Assist, 大学院・理学研究科, 助手 (90273218)
SANDA Ichiro Nagoya University, Graduate Course of Particle and Astrophysical Science, Profes, 大学院・理学研究科, 教授 (60242806)
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| Project Period (FY) |
1996 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1998: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1997: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1996: ¥900,000 (Direct Cost: ¥900,000)
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| Keywords | Dynamical Symmetry Breaking / Composite Higgs / Strong Coupling Gauge Theory / Nonperturbative Solution / Four-Fermion Theory / Top Quark Condensate / Light-Front (Light-Cone) Quantization / Zero Mode / カイラル対称性 / トップクォーク擬縮 / 電弱対称性 |
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| Research Abstract |
One of the most urgent problems in particle physics is the origin of mass. The present research project aimed at revealing the origin of mass based on the composite Higgs model, or the dynmamical symmetry breaking of the chiral symmetry. The main issue of us was to construct a unified model based on the strongly coupled gauge theories as well as to investigate a new class of field theories with nontrivial phase structure.
The top quark condensate we proposed long ago would be the starting point for such a purpose. We studied a possibility to reduce the original prediction of the top quark mass in this model which turned out somewhat larger than the experimental result. Based on the renormalizability argument of the gauge four-fermion theory ("gauged Nambu-Jona-Lasinio (NJL) model) , we showed that in the framework of GUT the cutoff can be taken to infinity so as to reduce the top mass prediction of the top quark condensate ("Top-mode GUT").
Recently much has been known about the phase st
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ructure of the supersymmetric strongly coupled gauge theories. In this connection we studied phase structure of non-supersymmetric gauge theories, particularly QCD with large number of flavors which is expected to have an infrared fixed point. This we studied in terms of a new concept of "conformal phase transition" which we developed through analysis of the peculiar phase transition of the gauged NJL model.
As a nonperturbative approach to the strongly coupled system, we also studied light-cone quantization : we further developed the Discrete Light-Cone Quantization. (DLCQ) which was first introduced by Maskawa-Yamawaki and has been frequently discussed for solving QCD and recently studied also in the Matrix model for the M-theory/superstring. We further developed our previous work on the spontaneous symmetry breaking in this framework, and pointed out some difficulty with the continuous framework in contrast to DLCQ.
In connection with the present project, we organized a Monbusho-sponsored international workshop "Perspectives of Strong Coupling Gauge Theories" at Nagoya during November 13-16, 1996 which accommodated 115 participants (42 from oversea). Less
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