Study of B-meson decays at the KEKB-Factory

在《粒子物理学》中，由小林和益川提出的基于夸克三重态的图像非常成功，被认为是粒子“标准模型”的一部分。Kobayashi-Maskawa理论最初是在1973年提出的，用来解释在k介子衰变中观察到的CP破坏。证明Kobayashi-Maskawa理论的最关键和最令人信服的方法是在k介子衰变以外的过程中发现CP破坏。Sanda和Bigi注意到，如果寿命足够长，如果b介子混合足够大，CP违逆的影响可以是大的和可测量的。事实证明确实如此，20世纪80年代末开始了一项严肃的研究，通过实验来测量这种影响。沿着这条思路建造了一个b介子工厂，并于1999年开始了实验。加速器的性能一直在稳步提高，其亮度超过了设计目标，现在它是世界上最好的对撞束。随着加速器的卓越性能，贝尔实验已经按照它的设计运行，到2005年3月底产生了超过4亿个b介子对。由于庞大的数据样本，Belle实验在2001年成功地观测到了Sanda和Bigi提出的CP违背。这为声称Kobayashi-Maskawa理论的正确性提供了非常严格的基础，Belle合作已经在评审期刊上发表了120多篇科学论文。贝尔实验的研究已经开始寻找可能暗示存在超出标准模型的东西的影响。贝尔实验的成功是由于贝尔探测器的优异性能，特别是它的顶点探测器精确地测量了b介子寿命。该探测器由贝尔合作的国际团队建造、操作和改进。成功的关键还在于该量热计性能优异，能准确测量光子和电子产生的能量较少

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