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首页> 外文学位 >Measurements of CP violation and neutral kaon charge radius using long-lived kaon going to pion-antipion-positron-electron decays.
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Measurements of CP violation and neutral kaon charge radius using long-lived kaon going to pion-antipion-positron-electron decays.

机译：使用长寿命的钾离子去介子-正离子-正电子电子衰变来测量CP违规和中性钾离子电荷半径。

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摘要

CP violation and K0 charge radius were measured using KL → pi+pi -e+e - decays. Specifically, a unique CP-violating decay-plane asymmetry was measured along with the parameters of individual contributions to the decay invariant amplitude: (i) CP-conserving magnetic dipole direct emission form factor, (ii) CP-conserving K0 charge radius transition amplitude and (iii) an upper limit for the CP-violating electric dipole direct emission amplitude. The measurements were obtained from the data sample accumulated by KTeV experiment at Fermilab.; KTeV had two major goals: the measurement of direct CP violation parameter Re (epsilon'/epsilon) and the study of rare kaon decays. The state of the art detector was constructed, commissioned, operated and maintained by an international collaboration of scientists from fourteen institutions. The KL → pi +pi-e+e- data was accumulated over the 1997 and 1999 running periods. During that time hundreds of billions KL decays took place in the KTeV fiducial decay region.; In the analysis of the rare decay mode KL → pi +pi-e+e- 5241 candidate events were selected from the entire KTeV dataset. This data sample included an estimated background of n = 204 +/- 14 events. The data was analyzed using the method of maximum likelihood to obtain parameters of the decay invariant amplitude. Namely, coefficients of the magnetic dipole (M1) direct emission form factor g&d5;M1=1.11+/-0 .12stat+/-0.08 syst a1a2= -0.744+/-0.027stat+/- 0.032syst GeV2 and the amplitude of K0 charge radius (CR) transition gCR=0.163+/- 0.014stat+/-0.023 syst were measured; and an upper limit for the CP-violating electric dipole (E1) direct emission process gE1 gM1 0.0490%CL and gE1E ★g0.03 90%CL was determined. The result for gCR allowed to determine the approximate value of the mean square charge radius of K0 r2K0 =-0.077+/-0.007stat +/-0.011syst fm2 in a novel way. Using the measured values for g&d5;M1 and a1a2 the average of gM1 (over the observed range of energies of the e +e- pair was calculated gM1 E★g =0.74+/-0.04. Finally, using the above values for the individual contributions in the invariant amplitude of the decay, the CP-violating decay-plane asymmetry was measured A= 13.6+/-1.4stat +/-1.5syst %. This is the most precise measurement of this unique asymmetry. It is the largest CP violation effect ever observed and the only one ever observed in an angular variable.
机译：使用KL→pi + pi -e + e-衰减来测量CP违规和K0电荷半径。具体而言，测量了唯一的违反CP的衰变平面不对称性以及对衰变不变幅度的各个贡献参数：（i）保持CP的磁偶极子直接发射形状因子，（ii）保持CP的K0电荷半径跃迁幅度（iii）违反CP的电偶极子直接发射幅度的上限。测量是通过费米实验室KTeV实验积累的数据样本获得的。 KTeV有两个主要目标：测量直接CP违规参数Re（ε/ε）和研究稀有的kaon衰变。由来自14个机构的科学家组成的国际合作组织，构造，调试，操作和维护了最先进的探测器。 KL→pi + pi-e + e-数据是在1997年和1999年运行期间累积的。在此期间，在KTeV基准衰减区域发生了数千亿个KL衰减。在稀有衰减模式KL→pi + pi-e + e-5241的分析中，从整个KTeV数据集中选择了候选事件。该数据样本包括n = 204 +/- 14个事件的估计背景。使用最大似然法对数据进行分析，以获得衰减不变幅度的参数。即，磁偶极子（M1）直接发射形状系数g＆d5; M1 = 1.11 +/- 0 .12stat +/- 0.08 syst a1a2 = -0.744 +/- 0.027stat +/- 0.032syst GeV2和K0电荷半径的幅度（CR）转换gCR = 0.163 +/- 0.014stat +/- 0.023 syst；并确定了违反CP的电偶极子（E1）直接发射过程的上限gE1 gM1 <0.0490％CL和gE1E＆bigstar; g <0.03 90％CL。 gCR的结果允许以新颖的方式确定K0 r2K0 = -0.077 +/- 0.007stat +/- 0.011syst fm2的均方电荷半径的近似值。使用g＆d5; M1和a1a2的测量值，计算出gM1的平均值（在观察到的e + e对能量范围内），计算得出gM1 E＆bigstar; g = 0.74 +/- 0.04。在衰减不变幅度中的贡献，测量到违反CP的衰减平面不对称性A = 13.6 +/- 1.4stat +/- 1.5syst＆percnt;这是这种独特不对称性的最精确测量，它是最大的曾经观察到CP违例效应，并且在角度变量中也观察到唯一的一个。

著录项

  • 作者

    Golossanov, Alexander.;

  • 作者单位

    University of Virginia.;

  • 授予单位 University of Virginia.;
  • 学科 Physics Elementary Particles and High Energy.
  • 学位 Ph.D.
  • 年度 2005
  • 页码 178 p.
  • 总页数 178
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 高能物理学;
  • 关键词

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