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Measurements of φdecay in nuclear matter

核物质中 φ 衰变的测量

基本信息

批准号：
08404013
负责人：
EN'YO Hideto
金额：
$ 18.69万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08404013/
关键词：
φ meson Chiral Symmetry Nuclear Matter Nuclear Media Effect Electron Pair Invariant Mass 中粒子ガスチェレンコフ

项目摘要

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.

在QCD中，强子被描述为约束价夸克的束缚态，它们由于手性对称性的自发破断而获得有效质量。这一机制决定了强子在自由空间中的性质，如质量和衰变宽度。如果真空结构从自由空间的结构改变，这些性质也应该改变。本项目旨在获得第一个实验结果来回答这些源于手性对称恢复的理论期望是否存在。1998年，我们安装了最后一批探测器、后置气体切伦科夫计数器和后置电磁量热计，完成了光谱仪的建设。在1997年，我们进行了测试运行，只关注φ→K γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ γ。自1998年以来，我们开始同时对φ→e D1+ D1- D1和φ→K D1+ D1- D1衰减模式进行数据采集。对1997年数据的分析已经完成。研究结果在多个国际会议上发表，并发表了Yokkaichi博士的博士论文和相关论文。1997年的数据在统计上不够充分，因此我们只能报告φ生产的核质量依赖性。然而，从1998-1999年的数据中，我们可以得到φ介子的中位衰减特征，其中包含了矢量介子的中位宽度和位移信息。研究结果将在几次会议上报告。本报告包括迄今为止已报道的科学材料，也包括在这个项目中开发的特殊探测器的发展成果。