权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Study of time reversal invariance in K decays

K衰变时间反演不变性的研究

基本信息

批准号：
11694101
负责人：
IMAZATO Jun
金额：
$ 2.94万
依托单位：
High Energy Accelerator Research Organization
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

项目摘要

The research consisted of the KEK-PS experiments E246 and E470. The E246 experiment was searching for T-violating muon polarization (P_γ) in K^+→π^0μ^+νdecay (K_<μ3> using the superconducting toroidal spectrometer setup in conjunction with a stopped K^+ beam. It was aimed to carry out a measurement with small systematic errors. We performed data taking in 1999 and 2000 using 1600 hours of beam time. In 2001 we continued data analysis and obtained a result of P_T= -0.0033±0.0117(stat)±0.003(syst) combined with our previous result and reported in a conference. The systematic errors of the 1998 results were further studied carefully. The data from the 1999 and 2000 runs were also analyzed and a preliminary result of P_T was obtained.One of the byproduct physics from this stopped K^+ experiment is the branching ratio measurement of the direct emission in K^+→π^+π^0γ decay. For an optimized trigger condition run, a new experiment was approved as E470 and it ran in the fall of 2001 for 960 hours. The data taking was successful and the branching ratio of the order of magnitude of 10^<-5> is expected to be determined with an accuracy of about 10 %. As another byproduct channel of E246, K^+→π^0e^+νdecay (K_<e3> was studied further to constrain the exotic scalar and tensor couplings. The values of f_R/f_+(0)=0.0040±0.0160(stat)±0.0067(syst) and f_T/f_+(0)=0.019±0.080(stat)±0.038(syst) were obtained. The decay width ratio of the two channels, Γ(K_<e3>)/Γ(K_<μ3>), was also analyzed and determined the q^2-dependent coefficient of f_0 form factor of the K_</3> decay to be λ_0 =0.019±0.005(stat)±0.004 (syst).

研究包括KEK-PS实验E246和E470。E246实验在K^+→π^0μ^+ν衰变（K_<μ3>）中寻找违反t的μ子极化（P_γ），实验采用超导环形谱仪与K^+束流相结合。它的目的是进行一个系统误差很小的测量。我们在1999年和2000年使用1600小时的波束时间进行了数据采集。2001年，我们继续进行数据分析，结合我们之前的结果，得到P_T= -0.0033±0.0117（stat）±0.003（syst）的结果，并在会议上报告。进一步仔细研究了1998年结果的系统误差。对1999年和2000年的运行数据进行了分析，得到了P_T的初步结果。停止K^+实验的副产物之一是测量K^+→π^+π^0γ衰变中直接发射的分支比。为了优化触发条件运行，一个新的实验被批准为E470，并在2001年秋天运行了960小时。数据采集是成功的，分支比的数量级为10^<-5>，预计精度约为10%。作为E246的另一个副产物通道，我们进一步研究了K^+→π^0e^+ν衰变（K_<e3>）来约束奇异的标量和张量耦合。f_R/f_+(0)=0.0040±0.0160（stat）±0.0067(syst), f_T/f_+(0)=0.019±0.080（stat）±0.038（syst）。分析了两个通道的衰减宽度比Γ(K_<e3>)/Γ（K_<μ3>），确定了K_</3>衰减的f_0形因子q^2依赖系数为λ_0 =0.019±0.005（stat）±0.004 （syst）。