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

在该研究计划中，在KEK质子同步加速器上进行了E246“寻找T破坏横向μ子偏振”和E470“K^+→π^0π^+γ衰变直接发射的分支比测量”的两个实验。，P_T本质上是T奇数，是与CP破坏相关的重要量，因为标准模型对PT没有贡献，所以它是一个非常敏感的探针。在本工作中，对 2000 年之前获取的数据进行了仔细的数据分析，并深入研究了横向偏振及其物理参数 Im 的最终结果，即 P_T = -。 0.0017 ±0.0023（统计）±0.0011（系统），Imψ = -0.0055 ±0.0071（统计）±0.0036 (syst)，这与零一致，表明没有 T 违规。在 E470 实验中，在精确的光谱测量中提取了 K^+ →π^0π^+γ 的直接发射分量，这是一种手性异常跃迁。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，但与之前的飞行中衰减数据相矛盾，作为副产品，研究了 K^+→π^0π^0e^+ν 衰减，并从提取的 216 个事件中确定了形状因子，尽管统计精度仍然不好。，并建立了形式主义来推导 π-π 散射长度。由于人们期望光束高 100 倍，因此对目前正在建设中的 J-PARC 进行 kaon 衰变实验使用停止 K^+ 光束的可能性进行了研究。对于 T 破坏 μ 子极化实验，不仅要测量 K^+ →π^0μ^+ν 衰变，还要测量 K^+ →π^0μ^+ν 衰变，这将变得很重要。 K^+→μ^+νγ 衰变，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，并研究了几个衰变通道及其物理案例。