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Study of kaon decays using stopped positive kaons at the KEK proton synchrotron

使用 KEK 质子同步加速器中停止的正 kaon 进行 kaon 衰变研究

基本信息

批准号：
14540285
负责人：
IMAZATO Jun
金额：
$ 2.11万
依托单位：
High Energy Accelerator Research Organization (2004)The High Energy Accelerator Research Organization (2002-2003)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

In this research program two experiments of E246 'Search for T-violating transverse muon polarization' and E470 "Branching ratio measurement of K^+ → π^0π^+γ decay direct emission" were performed at the KEK proton synchrotron. The transverse polarization, P_T, which is T-odd in nature, is an important quantity related to CP violation. Since there is no contribution to PT from the standard model, It is a very sensitive probe of new physics beyond the standard model. In the present work careful data analysis was performed for the data which had already been taken by 2000 and systematic error were thoroughly studied. A final result of transverse polarization and its physics parameter Imξ were obtained as P_T = -0.0017 ±0.0023 (stat) ±0.0011 (syst), and Imξ = -0.0055 ±0.0071 (stat) ±0.0036 (syst), which were consistent with zero revealing no T violation. In the E470 experiment the direct emission component of K^+ →π^0π^+γ which is a chiral anomaly transition was extracted in a precise spec … More tral measurement. From about 4,000 extracted events, the branching ratio was determined to be BR(DE) = (6.1±2.5(stat) ±1.9(syst))X10^<-3> which was consistent with the recent BNL result but contradicting previous in-flight decay data. As a byproduct the K^+→π^0π^0e^+ν decay was studied, and from exracted 216 events a form factor was determined although the statistical accuracy was still not good, and formalism was established to deduce the π-π scattering length.The possibilities of kaon decay experiments to use stopped K^+ beam at J-PARC, now under construction, were investigated. Since one expects 100 times higher beam intensity there, not only quantitative but also qualitative improvements and developments of data will be pursued. Regarding the T-violation muon polarization experiment, it will become important to measure not only the K^+ →π^0μ^+ν decay but also the K^+→μ^+νγ decay, which are complementary in some theoretical models of CP violation. New detector systems were investigated and several decay channels were studied with their physics cases. Less

本研究计划在KEK质子同步加速器上完成了E246“寻找T破坏的μ子横向极化”和E470“K^+ → π^0π^+γ衰变直接发射的分支比测量”两个实验。横向极化P_T是与CP破坏有关的一个重要物理量，它的性质是T奇的。由于标准模型对PT没有贡献，因此它是对标准模型之外的新物理的一种非常灵敏的探索。在目前的工作中，仔细的数据分析，已采取的数据，2000年和系统误差进行了深入的研究。结果表明，横向极化及其物理参数Im_T = -0.0017 ±0.0023（stat）±0.0011（syst），Im_T = -0.0055 ±0.0071（stat）±0.0036（syst），与零值一致，表明没有T破坏。在E470实验中，我们精确地提取了K^+ →π^0π^+γ的直接发射分量，这是一个手征反常跃迁 ...更多信息标准测量从大约4，000个提取的事件中，确定分支比为BR（DE）=（6.1±2.5（stat）±1.9（syst））X10^<-3>，这与最近的BNL结果一致，但与之前的飞行中衰变数据相矛盾。研究了K^+→π^0π^0e^+ν衰变的副产物，从提取的216个事例中确定了形状因子，虽然统计精度还不高，但建立了推导π-π散射长度的形式体系，研究了在正在建设的J-PARC上利用停止的K^+束进行K ~+衰变实验的可能性。由于人们预期那里的光束强度要高出100倍，因此不仅要在数量上而且要在质量上改进和发展数据。在T破坏μ子极化实验中，不仅要测量K^+ →π^0μ^+ν衰变，而且要测量K^+→μ^+νγ衰变，这在CP破坏的一些理论模型中是互补的。研究了新的探测器系统，并对几种衰变通道进行了物理分析。少