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2000 Fiscal Year Final Research Report Summary

Study of CP Violation in Neutral Kaon System

Research Project

Project/Area Number 11694078
Research Category

Grant-in-Aid for Scientific Research (B).

Allocation TypeSingle-year Grants
Section一般
Research Field 素粒子・核・宇宙線
Research InstitutionOsaka University

Principal Investigator

YAMANAKA Taku  Graduate School of Science, Osaka University Associate Professor, 大学院・理学研究科, 助教授 (20243157)

Co-Investigator(Kenkyū-buntansha) HARA Takanori  Graduate School of Science, Osaka University Assistant, 大学院・理学研究科, 助手 (70283827)
HAZUMI Masashi  Graduate School of Science, Osaka University Assistant, 大学院・理学研究科, 助手 (20263197)
NAGASHIMA Yorikiyo  Graduate School of Science Professor, 大学院・理学研究科, 教授 (90044768)
INAGAKI Takao  High Energy Accelerator Research Organization, Institute of Particle and Nuclear Studies, Professor, 素粒子原子核研究所, 教授 (60044757)
Project Period (FY) 1999 – 2000
KeywordsCP Violation / Weak interaction / Rare K decays
Research Abstract

We ran KTeV experiment in 1996-1997, and have obtained the following results.
* We have established the existance of direct CP violation, CP violation in the decay itself, instead of in the K^0-K^0 mixing. This is based on the result that the double ratio between the four branching ratios of K_L, S→π^+π^-, π^0π^0 decays is deviated from unity by 7 standard deviations. Based on this result and the result by CERN experiments, Super Weak model was rejected as the sole source of CP violation.
* We have observed the CP violation in the distribution of angle between ee and ππ planes in the K_L→ππee decays. This is the first time that the CP violation was found in the kinematical distributions.
* New upper limits on the branching ratios were set for the CP violating rare decays, K_L→π^0ee, K_L→π^0μμ, and K_L→π^0vv.
* In addition, we have measured branching ratios and form factors for other rare K decays and hyperon decays.
In 1999-2000, we had the second run, and collected the same amount of data for K_<L,S>→ππ events, and 2-3 times the data for rare decays.
We are currently designing a new experiment to measure the CP violation parameter by using K_L→π^0vv decays. For this experiment, we measured the kaon and neutron flux and energy distributions by bombarding the target by 150GeV protons.

  • Research Products

    (20 results)

All Other

All Publications (20 results)

  • [Publications] A.Alavi-Harati et al.: "Study of the K_L→ππγDirect Emission Vertex"Physical Review Letters. 86. 761-764 (2001)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] A.Alavi-Harati et al.: "Search for the Decay K_L→π^0e^+e^-"Physical Review Letters. 86. 397-401 (2001)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] A.Alavi-Harati et al.: "Evidence for the Deay K_L→μμγγ"Physical Review. D62. 112001-1-112001-5 (2000)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] A.Alavi-Harati et al.: "Search for the Decay K_L→π^0μμ"Physical Review Letters. 84. 5279-5282 (2000)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] A.Alavi-Harati et al.: "Search for the Decay K_L→π^0νν using π^0→eeγ Decays"Physical Review. D61. 072006-072010 (2000)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] A.Alavi-Harati et al.: "Observation of CP Violation K_L→ππee Decays"Physical Review Letters. 64. 408-411 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] A.Alavi-Harati et al.: "π^0→ee using K_L→3π^0 Decays in Flight"Physical Review Letters. 83. 922-925 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] A.Alavi-Harati et al.: "Measurement of the Decay K_L→π^0γγ"Physical Review Letters. 83. 917-920 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] A.Alavi-Harati et al.: "Observation of Direct CP Violation in K_<L,S>→ππ Decays"Physical Review Letters. 83. 22-27 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] J.Adams et al.,: "Search for the Decay K_L→π^0νν"Physics Letters. 447. 240-243 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] A.Alavi-Harati et al.: "Study of the K_L→ππγ Direct Emission Vertex"Phys.Rev.Lett. 86. 761-764 (2001)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] A.Alavi-Harati et al.: "Search for the Decay K_L→π^0e^+e^-"Phys.Rev.Lett.. 86. 397-401 (2001)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] A.Alavi-Harati et al.: "Evidence for the Deay K_L→μμγ"Phys.Rev.. D62. 112001-1-112001-5 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] A.Alavi-Harati et al.: "Search for the Decay K_L→π^0μμ"Phys.Rev.Lett.. 84. 5279-5282 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] A.Alavi-Harati et al.: "Search for the Decay K_L→π^0νν using π^0→eeγDecays"Phys.Rev.D. 61. 072006-072010 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] A.Alavi-Harati et al.: "Observation of CP Violation in K_L→ππee Decays"Phys.Rev.Lett.. 64. 408-411 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] A.Alavi-Harati et al.: "π^0→ee using K_L→3π^0 Decays in Flight"Phys.Rev.Lett.. 83. 922-925 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] A.Alavi-Harati et al.: "Measurement of hte Decay K_L→π^0γγ"Phys.Rev.Lett.. 83. 917-920 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] A.Alavi-Harati et al.: "Observation of Direct CP Violation in K_L, S→ππ Decays"Phys.Rev.Lett.. 83. 22-27 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] J.Adams et al.: "Search for the Decay K_L→π^0νν"Phys.Lett.. 447. 240-243 (1999)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 2002-03-26  

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