Study of time reversal invariance in K decays

K衰变时间反演不变性的研究

• 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
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-11694101/
• 关键词: Kaon decay; K_<μ3> decay; Muon transverse polarization; Time reversal inveriance; Toroidal spectrometer; KEK-PS; 対称性の破れ; CP対称性の破れ; Kμ3崩壊; 形状因子; Ke3崩壊; K^+→π^+π^0γ崩壊; ミュンン偏極; 横偏極; K_<e3>崩壊; KEK陽子加速器; CP不変性の破れ; ミュオン偏極; K_<π3>崩壊

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).

该研究包括KEK-PS实验E246和E470。E246实验是利用超导环形谱仪装置和停止的K^+电子束，在K^+→π^0μ^+ν衰变（K <μ3>）中寻找T破坏μ子极化（P_γ）。其目的是进行具有小系统误差的测量。我们在1999年和2000年使用1600小时的光束时间进行了数据采集。2001年我们继续对数据进行分析，并结合我们以前的结果，得到P_T= -0.0033 0. 0117（stat）±0.003（syst）。进一步仔细研究了1998年结果的系统误差。还分析了1999年和2000年运行的数据，得到了P_T的初步结果。这次停止的K^+实验的副产物物理之一是K^+→π^+π ^0 γ衰变中直接发射的分支比测量。对于优化的触发条件运行，一项新的实验被批准为E470，并于2001年秋季运行了960小时。数据采集是成功的，并且预期以约10%的准确度确定10 μ m数量级的分支比<-5>。作为E246的另一个副产物通道，K^+→π^0e^+ν衰变（K_）被<e3>进一步研究，以约束奇异标量和张量耦合。测得fR/f+（0）=0.0040±0.0160（stat）±0.0067（syst）和fT/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_&lt;μ3&gt;），并确定了K_衰减的f_0形状因子与q^2有关的系数</3>为λ_0 =0.019±0.005（stat）±0.004（syst）。

项目成果

S.Shimizu et al.: "Test of exotic scalar and tensor couplings in Κ^+→π^0e^+ν decay"Phys.Letters. B495. 33 (2000)

S.Shimizu 等人：“Κ^+→π^0e^+ν 衰变中的奇异标量和张量耦合测试”Phys.Letters 33 (2000)。

Y.H.Shin et al.: "A kinematically completee measureiment of Κ^+→π^+π^0π^0 decays"Euro Phys.J. C12. 627 (2000)

Y.H.Shin 等人：“Κ^+→π^+π^0π^0 衰变的运动学完整测量”Euro Phys.J. 627 (2000)。

Y. H. Shin et al.: "Kinematically complete measurement of K^+→π^0π^0π^+ decays"Zeitschrift fuer Physik C. (in press). (2000)

Y. H. Shin 等人：“K^+→π^0π^0π^+ 衰减的运动学完整测量”Zeitschrift fuer Physik C.（出版中）。

Yu. Kudenko and A.N. Khotjantsev: "A New Method for Measurement of T-violating Muon Plarization in K^+ Decays"Nuclear Physics. 63. 1 (2000)

于。

D. V. Dementyev et al.: "CsI(T1) photon detector with PIN photodiode readout for a Km3 T-violation experiment"Nuclear Instruments and Method in Physics Resesrch. A440. 151-171 (2000)

D. V. Dementyev 等人：“用于 Km3 T 破坏实验的具有 PIN 光电二极管读数的 CsI(T1) 光子探测器”核仪器和物理研究方法。