Measurements of φdecay in nuclear matter

在QCD中， Hadrons被描述为一个被确认的Valence的边界状态，因为它获得了有效的质量，导致了手性对称性的自发性破坏。这种机制决定了自由空间中的哈龙的属性，如质量和衰变宽度。如果真空结构在自由空间的性质中也应该改变，这个项目的目标是获得第一个实验结果，可以回答从手性对称性恢复中产生的理论期望是存在还是不存在的，我们将在1998年完成光谱仪构造，安装最后的探测器、后气体-Cherenkov计数器和后电磁辐射计。在1997年，我们只执行了测试运行，专注于φ → KI-D1 + KI-D1的衰变模式。自1998年以来，我们已经开始采取两种相同数据的运行φ → e y D1+ y D1 e y D1 and φ → y D1+ y D1 k y D1 D1 day modes.1997年数据已完成的分析。在几次国际会议上报告了结果，以及Yokkaichi博士和相关论文发表了Bean的博士论文。1997年的数据从统计上来说还不够，因为我们只能报告核质量对φ生产的依赖。从1998-1999年的数据来看，无论如何，我们可以获得介质衰减的特征，将介质宽度和矢量介质的变化传递给介质。这些结果是在几次会议上报告的，本报告包括了迄今为止报告的科学材料，也包括了在此项目中开发的特殊探测器的开发结果。

In QCD, hadrons are described as a bound state of confined valence quarks which obtained the effective mass due to the spontaneous breaking of the chiral symmetry. This mechanism determines the properties of hadrons in free space, such as the mass and the decay width. If the vacuum structure was changed from that in free space those properties should also change.This project aims to obtain the first experimental results which can answer whether such theoretical expectations originated from the chiral symmetry restoration are exist or not.We have completed the spectrometer construction in 1998 by installing the last detectors, the rear gas-Cherenkov counters and the rear EM-calorimeters. In 1997, we have performed the test run focusing only to the φ → KィイD1+ィエD1KィイD1-ィエD1 decay mode. Since 1998, we have started simultaneous data taking runs for both φ → eィイD1+ィエD1eィイD1-ィエD1 and φ → KィイD1+ィエD1KィイD1-ィエD1 decay modes.The analysis of the 1997 data was completed. The results are reported in several international conferences, and the PhD thesis of Dr. Yokkaichi and the associated paper have bean published. The 1997 data was not statistically enough so that we could only report the nuclear mass-dependence of the φ production. From the 1998-1999 data, however, we could obtain the signature of in-medium decay of φ meson which carries the information of in-medium width and shift of the vector mesons. The results are being reported in several conferences.This report includes the scientific materials which have been reported so far, and also includes outcomes from the developments of special detectors developed in this project.