2006 Fiscal Year Final Research Report Summary
Study of CP violation originated of mixing through FCNC decays of the B meson
| 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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| Keywords | FCNC / CP violation / B meson / Beyond the standard model / B factory / Unitaritty triangle / Kobayashi-Maskawa Mechanism / KEKB accelerator |
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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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