Study of CP violation originated of mixing through FCNC decays of the B meson

B 介子 FCNC 衰变混合引起的 CP 破坏研究

基本信息

批准号：
16340069
负责人：
WATANABE Yasushi
金额：
$ 10.5万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-16340069/
关键词：
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

项目摘要

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.

该项目的目的是通过测量各种B中膜衰减中的CP违规参数来寻找超出粒子物理标准模型的提示。在衰减中，FCNC（变化的中性电流）衰减对此目的最敏感，因为FCNC过程是通过尚不确定的新粒子可以贡献的环图发生的。它的效果可以大量修改CP违规参数。为了比较来自各种b膜衰减的CP违规参数，重要的是通过准确测量它们来确定其标准值。这是我们首先集中精力衡量重要的CP违规参数之一φ2。我们已经研究了衰减过程，即π^+π^ - ，（ρπ）^0，ρ^+ρ^ - 并成功地以约10％的精度进行测量。获得的值为（97±11）°，它与其他间接测量非常吻合，并且与标准模型中的Kobayashi-Maskawa机制一致。关于FCNC衰减渠道，我们无法直接完成投资。但是，我们通过各种讨论和纸质写作为他们的分析做出了很大的贡献。粒子物理学的标准模型已于1970年代中期建立。这是一个强大而美丽的理论，描述了自然界中存在的四分之三。 1973年，Kobayashi和Maskawa自然地将CP违规纳入了标准模型中。但是，实验证明非常困难。 Kek-B工厂加速器提供了世界上最高的光度，这使得这类艰难的实验。