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Study of Elementary Particles Using OPAL Detector at LEP

Research Project

Project/Area Number 04044040
Research Category

Grant-in-Aid for international Scientific Research

Allocation TypeSingle-year Grants
SectionJoint Research
Research InstitutionThe University of Tokyo

Principal Investigator

KOBAYASHI Tomio  Faculty of Science, The University of Tokyo, Professor, 理学部, 教授 (50126059)

Co-Investigator(Kenkyū-buntansha) MORII Masahiro  Faculty of Science, The University of Tokyo, assistant, 理学部, 助手 (50242095)
MICHELINI Aldo  CERN(Conseil europeen pour la Recherche nucleaire), Professor, 素粒子実験部門, 主任研究員
SASAKI Makoto  Faculty of Science, The University of Tokyo, assistant, 理学部, 助手 (40242094)
TSUKAMOTO Toshio  Faculty of Science, The University of Tokyo, assistant, 理学部, 助手 (40217287)
MORI Toshinori  Faculty of Science, The University of Tokyo, assistant, 理学部, 助手 (90220011)
KAWAGOE Kiyotomo  Faculty of Science, The University of Tokyo, assistant, 理学部, 助手 (40183785)
MASHIMO Tetsuro  Faculty of Science, The University of Tokyo, assistant, 理学部, 助手 (60181640)
KAWAMOTO Tatsuo  Faculty of Science, The University of Tokyo, assistant, 理学部, 助手 (80153021)
TAKESHITA Tohru  Faculty of Liberal Arts, The University of Shinshu, Associate professor, 教養部, 助教授 (70154995)
KOMAMIYA Sachio  Faculty of Science, The University of Tokyo, Associate professor, 理学部, 助教授 (80126060)
TAKEDA Hiroshi  Faculty of Science, The University of Kobe, Professor, 理学部, 教授 (30126114)
ORITO Shuji  Graduate School of Science, The University of Tokyo, Professor, 大学院理学系研究科, 教授 (10092173)
ALDO Micheli  欧州原子核研究機構素粒子実験部門, 主任研究員
Project Period (FY) 1992 – 1993
Project Status Completed (Fiscal Year 1993)
Budget Amount *help
¥20,000,000 (Direct Cost: ¥20,000,000)
Fiscal Year 1993: ¥10,000,000 (Direct Cost: ¥10,000,000)
Fiscal Year 1992: ¥10,000,000 (Direct Cost: ¥10,000,000)
KeywordsCERN / Electron-positron Collider LEP / Z^0 boson / the Standard Model / Top Quark / Higgs boson / gamma lepton / Bottom Quark / 大型電子・陽電子衝突装置LEP / Z゚粒子 / 標準理論 / 相互作用 / トップ・クォーク / 大統一理論
Research Abstract

The OPAL experiment, in which we are participating, is one of the four major experiments at the CERN large electron-positron collider(LEP), which started operation in 1989 to study e^+e^- reactions in the vicinity of the Z^0 boson resonance. The performance of LEP has been improving year after year. The OPAL experiment has been also very successful, and we collected 770k Z^0 events(peak only)in 1992 and 730k Z^0 events(peak and off-peak)in 1993, respectively. The number of Z^0 events from the beginning of the experiment now amounts to more than 2 million events. Not only the number of events is increased, but also the data quality is much improved with newly introduced detector elements as well as with better understanding of the detector.
The important results are listed below.
1. The Z^0 mass was determined with the best precision, by reducing the ambiguity of the beam energy from 20 MeV to 6 MeV. The standard model was tested with the measurements of Z^0 properties (total decay width, partial decay widths, forward-backward asymmetries of lepton-pair and quark pair productions). The top quark mass was confirmed to be about 150 GeV. The grand unified theory was tested with the measured coupling constants of the electroweak and strong interactions.
2. Two problems on gamma lepton were solved with the precise measurements of the branching fractions and the lifetime of gamma lepton.
3. A variety of bottom quark properties (Z^0 partial decay width, forward-backward asymmetry of pair production, lifetimes of bottomed mesons and baryons, and oscillation of neutral bottomed meson)were measured with outstandingly good precision.
4. The Higgs boson, elementary scalar particle in the standard model, is found to be heavier than 63 GeV. We obtained negative result on new particle with about 60 GeV mass, which had been suggested by the anomalous mass peak of two photons reported by the L3 group.

Report

(2 results)
  • 1993 Final Research Report Summary
  • 1992 Annual Research Report

Research Products

(51 results)

All Other

All Publications

  • [Publications] 「研究成果報告書概要(和文)」より

    • Related Report
      1993 Final Research Report Summary
  • [Publications] 「研究成果報告書概要(和文)」より

    • Related Report
      1993 Final Research Report Summary
  • [Publications] 「研究成果報告書概要(和文)」より

    • Related Report
      1993 Final Research Report Summary
  • [Publications] 「研究成果報告書概要(和文)」より

    • Related Report
      1993 Final Research Report Summary
  • [Publications] 「研究成果報告書概要(和文)」より

    • Related Report
      1993 Final Research Report Summary
  • [Publications] 「研究成果報告書概要(和文)」より

    • Related Report
      1993 Final Research Report Summary
  • [Publications] 「研究成果報告書概要(和文)」より

    • Related Report
      1993 Final Research Report Summary
  • [Publications] 「研究成果報告書概要(和文)」より

    • Related Report
      1993 Final Research Report Summary
  • [Publications] 「研究成果報告書概要(和文)」より

    • Related Report
      1993 Final Research Report Summary
  • [Publications] 「研究成果報告書概要(和文)」より

    • Related Report
      1993 Final Research Report Summary
  • [Publications] 「研究成果報告書概要(和文)」より

    • Related Report
      1993 Final Research Report Summary
  • [Publications] 「研究成果報告書概要(和文)」より

    • Related Report
      1993 Final Research Report Summary
  • [Publications] 「研究成果報告書概要(和文)」より

    • Related Report
      1993 Final Research Report Summary
  • [Publications] 「研究成果報告書概要(和文)」より

    • Related Report
      1993 Final Research Report Summary
  • [Publications] 「研究成果報告書概要(和文)」より

    • Related Report
      1993 Final Research Report Summary
  • [Publications] 「研究成果報告書概要(和文)」より

    • Related Report
      1993 Final Research Report Summary
  • [Publications] 「研究成果報告書概要(欧文)」より

    • Related Report
      1993 Final Research Report Summary
  • [Publications] 「研究成果報告書概要(欧文)」より

    • Related Report
      1993 Final Research Report Summary
  • [Publications] 「研究成果報告書概要(欧文)」より

    • Related Report
      1993 Final Research Report Summary
  • [Publications] 「研究成果報告書概要(欧文)」より

    • Related Report
      1993 Final Research Report Summary
  • [Publications] 「研究成果報告書概要(欧文)」より

    • Related Report
      1993 Final Research Report Summary
  • [Publications] 「研究成果報告書概要(欧文)」より

    • Related Report
      1993 Final Research Report Summary
  • [Publications] 「研究成果報告書概要(欧文)」より

    • Related Report
      1993 Final Research Report Summary
  • [Publications] 「研究成果報告書概要(欧文)」より

    • Related Report
      1993 Final Research Report Summary
  • [Publications] 「研究成果報告書概要(欧文)」より

    • Related Report
      1993 Final Research Report Summary
  • [Publications] 「研究成果報告書概要(欧文)」より

    • Related Report
      1993 Final Research Report Summary
  • [Publications] 「研究成果報告書概要(欧文)」より

    • Related Report
      1993 Final Research Report Summary
  • [Publications] 「研究成果報告書概要(欧文)」より

    • Related Report
      1993 Final Research Report Summary
  • [Publications] 「研究成果報告書概要(欧文)」より

    • Related Report
      1993 Final Research Report Summary
  • [Publications] 「研究成果報告書概要(欧文)」より

    • Related Report
      1993 Final Research Report Summary
  • [Publications] 「研究成果報告書概要(欧文)」より

    • Related Report
      1993 Final Research Report Summary
  • [Publications] 「研究成果報告書概要(欧文)」より

    • Related Report
      1993 Final Research Report Summary
  • [Publications]

    • Related Report
      1992 Annual Research Report
  • [Publications]

    • Related Report
      1992 Annual Research Report
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    • Related Report
      1992 Annual Research Report
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    • Related Report
      1992 Annual Research Report
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    • Related Report
      1992 Annual Research Report
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    • Related Report
      1992 Annual Research Report
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    • Related Report
      1992 Annual Research Report
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    • Related Report
      1992 Annual Research Report
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    • Related Report
      1992 Annual Research Report
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    • Related Report
      1992 Annual Research Report
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    • Related Report
      1992 Annual Research Report
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    • Related Report
      1992 Annual Research Report
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    • Related Report
      1992 Annual Research Report
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    • Related Report
      1992 Annual Research Report
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    • Related Report
      1992 Annual Research Report
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    • Related Report
      1992 Annual Research Report
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    • Related Report
      1992 Annual Research Report
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    • Related Report
      1992 Annual Research Report
  • [Publications]

    • Related Report
      1992 Annual Research Report

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Published: 1992-04-01   Modified: 2016-09-16  

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