Study of CP Violation in the Neutral Kaon System

中性Kaon体系中CP破坏的研究

• 批准号: 07044088
• 负责人: YAMANAKA Taku
• 金额: $ 4.93万
• 依托单位: Osaka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for international Scientific Research
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07044088/
• 关键词: weak interaction; CP violation; symmetry breaking; neutral K meson; rare decay; CsI calorimeter; data acquisition system; silicon strip detector; シリコンストップ検出器

The purpose of this project is to study the CP violation in the neutral kaon system from two fronts. One is to measure the double ratio of branching ratios of K_L, K_S*pi^0pi^0, and pi^+pi^- with a high precision (KTeV E832). The deviation of this ratio from unity is a proof of CP violation in the weak decay itself (direct CP violation). The other is to search for rare K_L decays where the effect of direct CP violation is dominant (KTeV E799).We have prepared the new experiments at Fermi National Accelerator Laboratory at U.S.A.. In particular, we were reponsible for the phototubes for the CsI electromagnetic calorimeter, fast data acquisition system, and a special photon veto counter.The experiment received the first neutral beam at the end of August 1995, and it was confirmed that the beam was clean as designed.We took data for E832 for 2 months in 1996, and started taking data for E799 from mid-January, 1997. With a couple of switchovers, we plan to take data till September, 1997. We expect to start having preliminary results sometime late 1997.We have also developed new silicon strip detectors for the B-factory experiment. After optimization with computer simulation, development of test system, and testing various prototypes, we have decided the final design. The mass production will start soon.

该项目的目的是从两个方面研究中性kaon系统中的CP违规行为。一种是用高精度测量k_l，k_s*pi^0pi^0和pi^+pi^ - 的分支比的双比（ktev e832）。该比率与统一的偏差是弱衰减本身违反CP的证明（直接违反CP）。另一个是寻找稀有的K_L衰变，在这种稀有的K_L衰减中，直接CP的效果是主要的（KTEV E799）。我们已经在美国的费米国家加速器实验室准备了新的实验。 1995年，已经证实，该光束是按照设计的清洁。我们在1996年获得了E832的数据2个月，并从1997年1月中旬开始获取E799的数据。随着几个切换，我们计划将数据收集到1997年9月。我们预计1997年晚些时候会开始进行初步的结果。我们还开发了新的Silicon Stricecon Stricect Dactorciact for B-Factory b-factorys B-Fact，B-Fact b-factory b-factory。在使用计算机仿真，开发测试系统和测试各种原型进行了优化之后，我们决定了最终设计。大规模生产将很快开始。

项目成果

B.Schwingenheuer, et al.: "CPT Tests in the Neutral Kaon System" Phys.Rev.Lett.74. 4376-4379 (1995)

B.Schwingenheuer 等人：“中性 Kaon 系统中的 CPT 测试”Phys.Rev.Lett.74。

M.B.Spencer,et al.: "Measurement of the Branching Ratio and Form-Factor of K_L→μ^+μ^-γ" Phys.Rev.Lett.74. 3323-3326 (1995)

M.B. Spencer 等人：“K_L→μ^+μ^-γ 的分支比和形状因子的测量”Phys.Rev.Lett.74 (1995)。

M.B.Spencer, et al.: "Measurement of the Branching Ratio and Form Factor of K_L*mu^+mu^-gamma" Phys.Rev.Let.74. 3323-3326 (1995)

M.B.Spencer 等人：“K_L*mu^ mu^-gamma 的分支比和形状因子的测量”Phys.Rev.Let.74。

J.N.Matthews, et al.: "New Measurement of the CP-Violation Parameter eta+-_<gamma>" Phys.Rev.Lett.75. 2803-2807 (1995)

J.N.Matthews 等人：“CP 破坏参数 eta -_<gamma> 的新测量”Phys.Rev.Lett.75。

P.Gu,et al.: "First Evidence for the Decay K_L→eeμμ" Phys.Rev.Lett.76. 4312-4315 (1996)

P.Gu 等人：“K_L→eeμμ 衰变的第一个证据”Phys.Rev.Lett.76 (1996)。