Measurement of CP violation parameter phi-2

CP违规参数phi-2的测量

基本信息

批准号：
13440074
负责人：
WATANABE Yasushi
金额：
$ 8.45万
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：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-13440074/
关键词：
Symmetry btw matter and antimatter (2) B factory CP Violation Kobayashi-Maskawa Mechanism Standard Model in particle Physics Experiment with accelerator B meson Asymmetric energy collider 非対称工ネルギー加速器物質・反物質間の対称性の破れ標準理論カビボ・小林・益川行列 B

项目摘要

The B factory accelerator KEKB is the world highest luminosity machine, achieving the design luminosity of 10^<34>cm^<-2>s^<-1> in May 2003, and still improving is luminosity record. The Belle experiment has upgraded the silicon vertex detector in summer 2003, and accumulates data in a good condition.About the research topic phi-2 measurement, we have analyzed and published the results on the π+ π- decay mode based on the data of integrated luminosity 253fb-14 four times larger than that of the previous publication. The parameter A and S are obtained as follows. A=+0.56±0.12(stat.)±0.06(syst.), S=-0.67±0.16(stat.)±0.06(syst.). Thus, we have established the existence of CP violation in this channel, too, following the discovery of CP violation in the J/ΨK decay mode in 2001. This result also strongly indicates that there is direct CP violation for the first time in B meson decay, because A is nonzero by more than 4 sigma significance. We also limit the arrowed range of phi2 by using the isospin relations. The result strongly supports the framework of the Kobayashi-Maskawa mechanism in the standard model, agreeing with other indirect determination.We have also looked at a1πdecay modes toward the aim of increasing the statistics in measuring the angle phi2 and established the existence of this decay mode determining the branching fraction for the first time. As the other contributions to the Belle experiment, we generated large amount of Monte Carlo simulation data using the purchased computer farm. Furthermore e also contributed in developing analysis tools : one gives high tagging efficiency in distinguishing the B meson from the anti-B meson, one to suppress the contribution of continuum events, etc. On the hardware side, we have developed the trigger system for the newly installed silicon vertex detector (SVD-2) and contributed much in improving the performance of the SVD-2.

B工厂加速器KEKB是世界上最高的发光机器，在2003年5月，达到10^<34> cm^<-2> s^<-1>的设计光度为10^<34> cm^<-2> s^<-1>，仍然有所改善是光度记录。 Belle实验已于2003年夏季升级了硅顶点探测器，并在良好的情况下积累了数据。根据研究主题PHI-2测量，我们根据Integrated Luminoration 253FB-14的数据比以前的出版物大于π+π-衰减模式进行了分析并发布了结果。参数A和S如下获得。 a =+0.56±0.12（stat。）±0.06（Syst。），s = -0.67±0.16（stat。）±0.06（Syst。）。这也是如此，在2001年的J/ψK衰减模式下发现CP违规后，我们也确定了CP违规的存在。该结果也强烈表明B Meson Decay中首次违反CP，因为A非零是非零的4个Sigma的重要性。我们还使用Isospin关系限制了PHI2的箭头范围。该结果强烈支持标准模型中Kobayashi-Maskawa机制的框架，同意其他间接确定。我们还研究了A1πdecay模式，目的是为了提高统计数据的统计数据，以测量角度PHI2并确定该衰减模式的存在，以确定第一次分支分数。作为Belle实验的其他贡献，我们使用购买的计算机农场生成了大量蒙特卡洛模拟数据。此外，E还为开发分析工具做出了贡献：一种在区分B介子和抗B介子方面具有很高的标记效率，一个是为了抑制持续事件等的贡献等。在硬件方面，我们为新安装的Silicon Vertex detector（SVD-2）开发了触发系统，并为改善了SVD-2-2-2-2-2-2。