Study of CP violation in B-meson decays

贝尔硅顶点探测器（Belle silicon vertex detector， SVD）在该基金和其他基金的共同支持下成功组装完成。在贝尔探测器中安装SVD后，进行了贝尔实验。该探测器已达到预期的工作性能，并为贝尔实验提供了最有价值的实验信息，特别是在b介子的衰变顶点位置上。这使我们能够测量b介子衰变的CP破坏参数。另一方面，人们注意到低动量粒子的跟踪效率需要提高。这可以通过在现有SVD的基础上再增加两层硅探测器来实现。我们正在设计升级后的SVD，并计划尽快展开研发工作，以便升级后的SVD可以在2002年夏季安装。在物理活动方面，我们首次观测到b介子衰变为φK态。这个过程可以通过所谓的“企鹅图”进行。因此，它将为研究这张图提供一个独特的场所。

Belle silicon vertex detector (SVD) was successfully built and assembled by the collaborative work supported by this fund and also other funds. The Belle experiment has been carried out after installing SVD in the Belle detector. This detector has been working with the expected performance and it has provided most valuable experimental information of the Belle experiment, especially on the decay vertex position of B-mesons. This enables us to measure the CP violation parameter of the B-meson decays.On the other hand, it has become noticed that the tracking efficiency for low momentum particles need to be improved. This can be made by having two more layers of the silicon detector to what we have for the present SVD.We are designing the upgraded SVD and we plan to start R＆D works soon so that the upgraded SVD can be ready for installation in the summer 2002.As for the physics activities, we could observe the B-meson decay into φK state for the first time. This is the process which can proceed through the so-called "Penguin diagram". Therefore it will provide a unique place for studying this diagram.