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1995 Fiscal Year Final Research Report Summary

Searches for exotic particles at HERA

Research Project

Project/Area Number 05044044
Research Category

Grant-in-Aid for international Scientific Research

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

Principal Investigator

YAMADA Sakue  Inst. for Nuclear Study The University of Tokyo, Prof., 原子核研究所, 教授 (70011658)

Co-Investigator(Kenkyū-buntansha) WOLF Gunter  DESY,Leading Roseacher, 主任研究員
SCIULLI Frank  Columbia Univ., Prof., 教授
CASHIMORE Roger  Oxford Univ., Prof., 教授
NAKAO Mikihiko  JSPS Postdoctoral Fellow, 学振特別研究員
SHINO Kazuo  Inst. for Nuclear Study, Res. Ass., 助手 (20092231)
KUZE Masahiro  Inst. for Nuclear Study, Res. Ass., 助手 (00225153)
TOKUSHUKU Katsuo  Inst. for Nuclear Study, Res. Ass., 助手 (80207547)
ISHII Takanobu  Inst. for Nuclear Study, Res. Ass., 助手 (90134650)
TSURUGAI Tatsumasa  Meijigakuin Univ., Gen. Edu., ・Lecturer, 一般教育部, 専任講師 (50267366)
HAMATSU Ryosuke  Tokyo Metropolitan Univ., Faculty of Science, Ass. Prof., 理学部, 助教授 (20087092)
HIROSE Tachisige  Tokyo Metropolitan Univ., Faculty of Science, Prof., 理学部, 教授 (70087162)
Project Period (FY) 1993 – 1995
KeywordsHERA / ZEUS / Deep inelastic scattering / exotic particle / excited fermion / contact interaction / W / Z boson / large rapidity gap / hard jet
Research Abstract

Searches for new particles and new phenomena were carried out through the ZEUS collaboration at the electron-proton collider HERA at DESY.During the fiscal year 1995, the collider was operated for physics at the total center of mass energy of 300 GeV from May to November. The ZEUS detector performed well to record a total luminosity of about 7 pb^<-1>. The data is now being reconstructed. In parallel analyzes of the data which had been obtained till last year have been continues giving the following results.
^<**>The cross sections of deep inelastic scattering have been measured both for the neutral current reactions and the charged current reactions. In the region for Q^2 above 10^4 GeV^2, the effect of the W/Z boson mass can be observed. The u-quark and the d-quark contributions could be separated through the comparison of the e ^-p and the e ^+p data. The cross sections are consistent with the expectations of standard model thus giving upper limits on the possible contact interactions. Depending on the type of coupling, the obtained limits on the cut-off ranges between 1000 GeV and 1800 GeV.
^<**>A systematic search for excited fermions have been made. No evidence was found and limits on the coupling constant was obtained for the mass range between 50 and 250 GeV.
^<**>Hard jet production in the photoreaction was investigated. This study is important in order to study W/Z production by means of their hadronic decays.
^<**>Hard isolated lepton (s) with a large transverse momentum was searched for. They give a clue for exotic particles. Some candidates were found which are consistent with the production and leptonic decay of W/Z bosons.
^<**>Systematic investigations of the events with a large rapidity gap were continued both for the deep inelastic scattering and the hard photoproduction.

  • Research Products

    (12 results)

All Other

All Publications (12 results)

  • [Publications] ZEUS Collaboration,M.Derrick et.al.: "A Search for excited fermions in electron-proton collisions at HERA" Zeitschrift fur Physik C. 65. 627-647 (1995)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] K.Sasaki,K.Tokushuku,Y.Yamazaki and S.Yamada: "Search for Signature of Dilepton Gauge Bosons in HERA and LEP-II-LHC" Physics Letters B. 345. 495-499 (1995)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] ZEUS Collaboration M.Derrick et.al.: "Dijet Cross Sections in Photoproduction at HERA" Physics Letters B. 348. 665-680 (1995)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] ZEUS Collaboration M.Derrick et.al.: "Measurement of Charged and Neutral Current e p Deep Inelastic Scattering Cross Sections at High Q^2" Physics Letters B. 75. 1006-1011 (1995)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] ZEUS Collaboration M.Derrick et.al.: "Diffractive Hard Photoproduction at HERA and Evidence for the Gluon Content of Pomeron" Physics Letters B. 356. 129-146 (1995)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] ZEUS Collaboration M.Derrick et.al.: "Measurement of αs from Rates in Deep Inelastic Scattering" Physics Letters B. 363. 201-216 (1995)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] ZEUS Collaboration, M.Derrick et. al.: "A Search for excited fermions in electron-proton collisions at HERA" Zeitschrift fur Physik C. 65. 627-647 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] K.Sasaki, K.Tokushuku, Y.Yamazaki and S.Yamada: "Search for Signature of Dilepton Gauge Bosons in HERA and LEP-II-LHC" Physics Letters B. 345. 495-499 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] ZEUS Collaboration M.Derrick et. al.: "Dijet Cross Sections in Photoproduction at HERA" Physics Letters B. 348. 665-680 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] ZEUS Collaboration M.Derrick et. al.: "Measurement of Charged and Neutral Current e'p Deep Inelastic Scattering Cross Sections at High Q^2" Physics Letters B. 75. 1006-1011 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] ZEUS Collaboration M.Derrick et. al.: "Diffractive Hard Photoproduction at HERA and Evidence for the Gluon Content of Pomeron" Physics Letters B. 356. 129-146 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] ZEUS Collaboration M.Derrick et. al.: "Measurement of deltas from Jet Rates in deeo Inelastic Scattering" Physics Letters B. 363. 201-216 (1995)

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

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Published: 1997-03-04  

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