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

在本研究项目中，我们在KEK质子同步加速器上进行了E246“寻找违反T的横向介子极化”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本质上是T-奇性的，是与CP破坏有关的一个重要物理量。由于标准模型对PT没有贡献，因此它是对超越标准模型的新物理的一个非常灵敏的探索。在目前的工作中，对截至2000年已经取得的数据进行了仔细的数据分析，并对系统误差进行了彻底的研究。得到了横向极化及其物理参数Imξ的最终结果：P_T=-0.0017±0.0023(STAT)±0.0011(SYST)，Imξ=-0.0055±0.0071(STAT)±0.0036(SYST)，与零一致，表明没有T破坏。在E470实验中，对手征反常跃迁K^+→π^0π^+γ的直接发射分量进行了精确的SPEC…提取更多的衡量标准。从大约4,000个提取的事件中，确定了分支比为BR(DE)=(6.1±2.5(STAT)±1.9(SYST))×10^-3&gT；这与最近的BNL结果一致，但与以前的飞行中衰减数据相矛盾。作为一个副产品，研究了K^+→π^0π^0E^+ν衰变，从提取的2 16个事件中确定了一个形状因子，尽管统计精度仍然不是很好，并建立了公式来推导π-π散射长度。由于人们预计那里的束流强度将高出100倍，因此不仅将追求数量上的改进，而且还将寻求数据的质量改进和发展。对于T破坏的Muon极化实验，不仅要测量K^+→π^0μ^+ν衰变，而且还要测量K^+→μ^+νγ衰变，这两个衰变在CP破坏的一些理论模型中是互补的。研究了新的探测系统，并用物理实例研究了几种衰变通道。较少

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