| Project/Area Number |
16340069
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Particle/Nuclear/Cosmic ray/Astro physics
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
WATANABE Yasushi Tokyo Institute of Technology, Graduate School of Science, professor (40126199)
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| Co-Investigator(Kenkyū-buntansha) |
ISHINO Hirokazu Tokyo Institute of Technology, Graduate School of Science, Assistant professor (90323782)
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| Project Period (FY) |
2004 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥16,400,000 (Direct Cost: ¥16,400,000)
Fiscal Year 2006: ¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 2005: ¥7,000,000 (Direct Cost: ¥7,000,000)
Fiscal Year 2004: ¥7,600,000 (Direct Cost: ¥7,600,000)
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| Keywords | FCNC / CP violation / B meson / Beyond the standard model / B factory / Unitaritty triangle / Kobayashi-Maskawa Mechanism / KEKB accelerator / 物質・反物質間の対称性の破れ / Bファクトリー / FCNC(香りを変える中性カレント) / 標準理論 / 希崩壊 |
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| Research Abstract |
The purpose of this project is to look for hints beyond the standard model of particle physics through measurements of CP violation parameters in various B meson decays. Among the decays, FCNC (Flavor Changing Neutral Current) decays are most sensitive for that purpose, because FCNC processes occur through a loop diagram where yet-unknown new particles can contribute. Its effect can modify CP violation parameters by a large amount. In order to compare CP violation parameters from various B meson decays, it is important to establish their standard values by measuring them accurately. Thus, we first focused our effort to measure one of the important CP violation parameters, Φ2. We have investigates the decay processes, π^+π^-,(ρ π)^0,ρ^+ρ^-and succeeded to measure it in about 10% accuracy. The obtained value is (97±11)°,which agrees well with other indirect measurements and is consistent with the Kobayashi-Maskawa mechanism in the standard model. Concerning on FCNC decay channels, we could not directly complete investigation. However, we contribute much to their analyses through various discussion and paper writing.
The standard model in particle physics has been established in the middle of 1970's. It is a powerful and beautiful theory describing three out of four forces existing in nature. CP violation has been naturally incorporated into the standard model by Kobayashi and Maskawa in 1973. However, experimental proof had been very difficult. The KEK-B factory accelerator has provided world highest luminosity, which has enabled this kind of difficult experiment.
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