Study of B-meson decays at the KEKB-Factory

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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