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Study of B-meson decays at the KEKB-Factory

KEKB 工厂 B 介子衰变研究

基本信息

批准号：
13440083
负责人：
TAKASAKI Fumihiko
金额：
$ 10.43万
依托单位：
Institute of Particle and Nuclear Studies (2004)The High Energy Accelerator Research Organization (2001-2003)
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 2004
项目状态：
已结题

项目摘要

In the Particle Physics, a picture based on three doublets of quarks, proposed by Kobayashi and Maskawa, is so successful that it is conceived as a part of the "Standard Model" of Particles. Originally Kobayashi-Maskawa theory was introduced in 1973 to explain the CP violation observed in the K-meson decays. The most crucial and convincing way of proving the Kobayashi-Maskawa theory is to find the CP violation in the processes other than the K-meson decays. Sanda and Bigi noticed that the effects of CP violation can be large and measurable if the life time is long enough and if the B-meson mixing is large. It turned out that this is really the case and the serious study has started in late 1980s to measure this effect experimentally.A B-meson factory was constructed along this line of consideration and the experiment has started in 1999. The performance of the accelerator has been improving steadily and its luminosity exceeded the design goal and it is now the world best colliding beam … More accelerator ever built.Along with the superb performance of the accelerator, the Belle experiment has been operated as it was designed and produces more that 400 million B-meson pairs by the end of March 2005. Thanks to the huge data sample, the Belle experiment has successfully observed the CP violation in 2001 as was proposed by Sanda and Bigi. This provides a very stringent basis for claiming the correctness of the Kobayashi-Maskawa theory, The Belle collaboration has already published more than 120 scientific papers in the refereed journals. The study by the Belle experiment has started to search for effects which may hint the existence of something beyond the standard model.The success of the Belle experiment is due to the excellent performance of the Belle detector, especially its Vertex detector to measure the B-meson lifetime accurately. This detector has been built, operated and improved by the international team of the Belle collaboration.The key of the success is also due to the excellent performance of the calorimeter to measure accurately the energy of photons and electrons produced Less

在《粒子物理学》中，小林和益川提出的基于三重夸克的图像非常成功，以至于它被认为是粒子“标准模型”的一部分。小林-益川理论最初于 1973 年提出，用于解释 K 介子衰变中观察到的 CP 破坏。证明小林-益川理论最关键、最有说服力的方法是在K介子衰变以外的过程中找到CP破坏。 Sanda 和 Bigi 注意到，如果寿命足够长并且 B 介子混合很大，则 CP 破坏的影响可能很大且可测量。事实证明，情况确实如此，并于20世纪80年代末开始认真研究实验测量这种效应。沿着这个考虑，建造了B介子工厂，并于1999年开始实验。加速器的性能稳步提高，其光度超过了设计目标，现在是世界上有史以来最好的对撞光束加速器。随着加速器的卓越性能，贝尔实验也得到了发展。到2005年3月，该实验按设计运行，产生了超过4亿个B介子对。凭借庞大的数据样本，Belle实验成功观测到了Sanda和Bigi提出的2001年的CP破坏。这为声称小林-益川理论的正确性提供了非常严格的依据，Belle 合作组织已在参考期刊上发表了 120 多篇科学论文。 Belle实验的研究已经开始寻找可能暗示超出标准模型的事物存在的效应。Belle实验的成功归功于Belle探测器的优异性能，特别是它的Vertex探测器能够准确测量B介子寿命。该探测器由Belle合作的国际团队建造、操作和改进。成功的关键还归功于量热计的优异性能，能够精确测量产生的光子和电子的能量。