权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

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.

本计画的目的是透过测量不同B介子衰变的CP破坏参数，寻找粒子物理标准模型之外的线索。在这些衰变中，FCNC（变味中性电流）衰变对这一目的最敏感，因为FCNC过程是通过一个回路图发生的，在这个回路图中，未知的新粒子可以做出贡献。其效果可以大量修改CP违规参数。为了比较不同B介子衰变的CP破坏参数，通过精确测量来建立它们的标准值是很重要的。因此，我们首先集中精力测量重要的CP破坏参数之一Φ2。我们研究了衰变过程π^+π^-，（ρ π）^0，ρ^+ρ^-，并成功地测量了它，精度约为10%。得到的结果为（97±11）°，与其它间接测量结果吻合较好，符合标准模型中的Kobayashi-Maskawa机制。关于FCNC衰变通道，我们不能直接完成研究。粒子物理学中的标准模型是在70年代中期建立起来的。这是一个强大而美丽的理论，描述了自然界中存在的四种力中的三种。1973年小林和Maskawa将CP破坏自然地纳入标准模型。然而，实验证明非常困难。KEK-B工厂的加速器提供了世界上最高的光度，使这种困难的实验成为可能。