1997 Fiscal Year Annual Research Report

電子・陽電子衝突装置LEP-IIでのOPAL測定器による素粒子の研究

Research Project

Project/Area Number	09044060
Research Institution	The University of Tokyo
Principal Investigator	小林富雄東京大学, 素粒子物理国際研究センター, 教授 (50126059)
Co-Investigator(Kenkyū-buntansha)	真下哲郎東京大学, 素粒子物理国際研究センター, 助手 (60181640) 森俊則東京大学, 素粒子物理国際研究センター, 助教授 (90220011) 川本辰男東京大学, 素粒子物理国際研究センター, 助教授 (80153021) 駒宮幸男東京大学, 素粒子物理国際研究センター, 教授 (80126060) 折戸周治東京大学, 理学系研究科, 教授 (10092173)
Keywords	LEP / LEP-II / OPAL / 鉛ガラスカロリメター / 標準理論 / Wボソン / ヒッグス粒子 / 超対称性理論
Research Abstract	世界最高エネルギーの電子陽電子衝突装置LEPは平成9年度には前年より更にエネルギーを増強し、衝突エネルギー183GeVで実験を行なった。LEPの性能も向上し、前年に比べて約3倍の衝突事象を生成した。OPAL測定器は、順調に動作し、東京大学が建設した、最も重要な構成要素の一つである鉛ガラスカロリメターも高性能を維持し質の高いデータを収集した。大量のデータによりW粒子の質量等の精密測定の制度が大きく向上した。同時に、高いエネルギーで初めて作り出されるかもしれないヒッグス粒子や新粒子の発見の可能性が大きく広がった。このデータを最大に生かし、測定精度や新粒子探索の感度を上げるため、解析方法の改良や、新しいテーマの研究を行った。主な成果としては: (1)約900個のW粒子対発生事象が得られた。W粒子の質量測定の精度は、4つのLEP実験の結果を合わせると、陽子反陽子加速器からの結果と同じ精度になった。これをLEP-IでのZ^0粒子の精密測定等と組み合わせて標準理論の整合性を高い精度でテストすることが可能になって来た。W粒子以外でも、標準理論で期待される各種の反応過程をもれなく測定し、新しいエネルギー領域で理論をテストした。これにより、標準理論からのずれを生むかもしない新物理の可能性について制限をつけた。 (2)標準理論に必要でありながら、未だに発見されていないヒッグス粒子を探索し、その質量がS4GeVより重いという結果を得た。また、各種の新粒子も幅広く探索した。特に、標準理論を越える理論として最も有力な超対称性理論は新しい粒子群を予言する。これらを系統的に探索した。今年度のデータからは新粒子の兆候は発見されなかったが、この事から逆に、これら新しい理論やその未知のパラメータについて厳しい制限を与えた。これらの結果は学術専門誌に発表するとともに、国際会議等で報告された。

Research Products
(42 results)

All Other

All Publications (42 results)

[Publications] The OPAL Collaboration: "Search for Supersymmetric Particres and Anomalous Four-Jet Production at √<S>=130 and 136 GeV at LEP" Z. Phys.C73. 201-216 (1997)
[Publications] The OPAL Cllaboration: "Strange Baryon Production in Hadronic Z^0 Decays" Z. Phys.C73. 569-585 (1997)
[Publications] The OPAL Collaboration: "Σ^+, Σ^0 and Σ^- Hyperon Prduction in Hadronic Z^0 Decays" Z. Phys.C73. 587-599 (1997)
[Publications] The OPAL Collaboration: "A Measurement of the Charm and Bottom Farward-Backward Asymmetries using D Mesons at LEP" Z. Phys.C73. 379-396 (1997)
[Publications] The OPAL Collaboration: "Search for Neutral Higgs Bosos in Z^0 Decays Using the OPAL Detector at LEP" Z. Phys.C73. 189-199 (1997)
[Publications] The OPAL Collaboration: "Inclusive Jet Production in Photon-Photon Collisions at √<S>=130 and 136 GeV" Z. Phys.C73. 433-442 (1997)
[Publications] The OPAL Collaboration: "A Measurement of the Average Bottom Haclron Lifetime" Z. Phys.C73. 397-408 (1997)
[Publications] The OPAL Collaboration: "Search for Excited Leptons in e^+e^- Collisions at √<S>=161 GeV" Phys. Lett.B391. 197-209 (1997)
[Publications] The OPAL Collaboration: "Search for Unstable Neutral and Charged Leptons in e^+e^- Collisions at √<S>=161 GeV" Phys. Lett.B393. 217-230 (1997)
[Publications] The OPAL Collaboration: "Measurement of the QED Structure Functions of the Photon Using Azimuthal Correlations at LEP" Z. Phys.C74. 49-55 (1997)
[Publications] The OPAL Collaboration: "Production of Fermion-pair Events in e^+e^- Collisions at 161 GeV Centre-of-wass Energy" Phys. Lett.B391. 221-234 (1997)
[Publications] The OPAL Collabration: "Photonic Events with Large Missing Energy in e^+e^- Collisions at √<S>=161 GeV" Phys. Lett.B391. 210-220 (1997)
[Publications] The OPAL Collaboration: "Analysis of Hadronic Final States and the Photon Structure Function F^r_2 in Deep Inelastic Electron-Photon Scattering at LEP" Z. Phys.C74. 33-48 (1997)
[Publications] The OPAL Collaboration: "Search for the Standard Moded Higgs Boson in e^+e^- Collisions at √<S>=161 GeV" Phys. Lett.B393. 231-244 (1997)
[Publications] The OPAL Collaboration: "A Mesurement of Vcb Using B^0→D^*+l^-rl Decays" Phys. Lett.B395. 128-140 (1997)
[Publications] The OPAL Collaboration: "An Improved Measurement of Rb Using a Double Tagging Method" Z. Phys.C74. 1-17 (1997)
[Publications] The OPAL Collaboration: "Measurement of the Semireptonic Branching Fraction of Inclusive b Baryon Decays to Λ" Z. Phys.C74. 423-435 (1997)
[Publications] The OPAL Collaboration: "Search for Charged Scalar Leptons Using the OPAL Detector at √<S>=161 GeV" Phys. Lett.B396. 301-314 (1997)
[Publications] The OPAL Collaboration: "Search for CP Violation in Z^0→τ^+τ^- and an Upper Limit on the Weak Dipole Moment o the τ Lepton" Z. Phys.C74. 403-412 (1997)
[Publications] The OPAL Collaboration: "B^* Production in Z^0 Decays" Z. Phys.C74. 413-422 (1997)
[Publications] The OPAL Collaboration: "Measurement of the Triple Gauge Boson Coupling αwφ from W^+W^- Production in e^+e^- Collisions at √<S>=161GeV" Phys. Lett.B397. 147-157 (1997)
[Publications] The OPAL Collaboration: "Measurement of the b Quark Forward-backward Asymmetry around the Z^0 Reak Using Jet Charge and Vertex Charge" Z. Phys.C75. 385-396 (1997)
[Publications] The OPAL Collaboration: "Study of φ (1020), D^*^± and B^* Spin Alnment in Hadronic Z^0 Decays" Z. Phys.C74. 437-449 (1997)
[Publications] The OPAL Collaboration: "QCD Studies with e^+e^- Annihilation Data at 161GeV" Z. Phys.C75. 193-207 (1997)
[Publications] The OPAL Collaboration: "A Measurement of the Hadronic Decay Current and the Vr-helicity in T^-→π^-π^-π^-Vr" Z. Phys.C75. 593-605 (1997)
[Publications] The OPAL Collaboration: "Production of D-Wave Charm and Charm-Strange Mesons in Hadronic Z^0 Decays" Z. Phys.C76. 425-440 (1997)
[Publications] The OPAL Collaboration: "A Study of B Meson Oscillations Using Hadronic Z^0 Decays Containing Leptons" Z. Phys.C76. 401-415 (1997)
[Publications] The OPAL Collaboration: "Search for Scalar TOP and Scalar Bottom Quarks at √<S>=170-172 GeV in e^+e^- Collisions" Z. Phys.C75. 409-420 (1997)
[Publications] The OPAL Collaboration: "An Upper Limit on the Branching Ratio for τ Decays into Seven Charged Particles" Phys. Lett.B404. 213-222 (1997)
[Publications] The OPAL Collaboration: "Measurement of the Branching Fractions and Foruard-Backward Asymmetries of the Z^0 of tje Z^0 into Light Quarks" Z. Phys.C76. 387-440 (1997)
[Publications] The OPAL Collaboration: "An Updated Study of B Meson Oscillations using Dilepton Events" Z. Phys.C76. 417-423 (1997)
[Publications] The OPAL Collaboration: "Measurement of the quarlt to photon Fragmentation Function through the Inclusive Production of Prompt Photons in Hadronic Z^0 Decays" Eur. Phys. J.C2. 39-48 (1998)
[Publications] The OPAL Collaboration: "Measurement of the Q^2 Evolution of the Photon Structure Function F^r_2" Phys. Lettt.B414. 387-401 (1997)
[Publications] The OPAL Collaboration: "Measurement of f(c→D^*+X), f(b→D^*+X) and Γcc / Γhad Using D^*^± Mesons" Eur. Phys. J.C1. 439-459 (1998)
[Publications] The OPAL Collaboration: "Spin Alignment of Leading K^* (892)^0 Mesons in Haclronic Z^0 Decays" Phys. Lett.B412. 210-224 (1997)
[Publications] The OPAL Collaboration: "Measurement of the Photon Stucture Function F^r_2 at low X" Phys. Lett.B412. 225-234 (1997)
[Publications] The OPAL Collaboration: "Multiplicity distributions of gluon and quark jets and tests of QCD analytic prediction" Eur. Phys. J.C1. 479-494 (1998)
[Publications] The OPAL Collaboration: "Multi-photon Fmal States in e^+e^- Collisions at √<S>=130-172 GeV" Eur. Phys. J.C1. 21-30 (1998)
[Publications] The OPAL Collaboration: "Search for the Standard Model Higgs Boson in e^+e^- Collisions at √<S>=161-172 GeV" Eur. Phys. J.C1. 425-438 (1998)
[Publications] The OPAL Collaboration: "Measurement of the WBoson Mass and W^+W^- Production and Decay Properties in e^+e^- Collisions at √<S>=172 GeV" Eur. Phys. J.C1. 395-424 (1998)
[Publications] The OPAL Collaboration: "Search for a Massive Di-photon Resonance at √<S>=91-172 GeV" Eur. Phys. J.C1. 31-43 (1998)
[Publications] The OPAL Collaboration: "Search for Unstable Heavy and Excited Leptons in e^+e^- Collisions at √<S>=170-172 GeV" Eur. Phys. J.C1. 45-64 (1998)

1997 Fiscal Year Annual Research Report

電子・陽電子衝突装置LEP-IIでのOPAL測定器による素粒子の研究

Principal Investigator

小林 富雄 東京大学, 素粒子物理国際研究センター, 教授 (50126059)

Research Products

[Publications] The OPAL Collaboration: "Search for Supersymmetric Particres and Anomalous Four-Jet Production at √<S>=130 and 136 GeV at LEP" Z. Phys.C73. 201-216 (1997)

[Publications] The OPAL Cllaboration: "Strange Baryon Production in Hadronic Z^0 Decays" Z. Phys.C73. 569-585 (1997)

[Publications] The OPAL Collaboration: "Σ^+, Σ^0 and Σ^- Hyperon Prduction in Hadronic Z^0 Decays" Z. Phys.C73. 587-599 (1997)

[Publications] The OPAL Collaboration: "A Measurement of the Charm and Bottom Farward-Backward Asymmetries using D Mesons at LEP" Z. Phys.C73. 379-396 (1997)

[Publications] The OPAL Collaboration: "Search for Neutral Higgs Bosos in Z^0 Decays Using the OPAL Detector at LEP" Z. Phys.C73. 189-199 (1997)

[Publications] The OPAL Collaboration: "Inclusive Jet Production in Photon-Photon Collisions at √<S>=130 and 136 GeV" Z. Phys.C73. 433-442 (1997)

[Publications] The OPAL Collaboration: "A Measurement of the Average Bottom Haclron Lifetime" Z. Phys.C73. 397-408 (1997)

[Publications] The OPAL Collaboration: "Search for Excited Leptons in e^+e^- Collisions at √<S>=161 GeV" Phys. Lett.B391. 197-209 (1997)

[Publications] The OPAL Collaboration: "Search for Unstable Neutral and Charged Leptons in e^+e^- Collisions at √<S>=161 GeV" Phys. Lett.B393. 217-230 (1997)

[Publications] The OPAL Collaboration: "Measurement of the QED Structure Functions of the Photon Using Azimuthal Correlations at LEP" Z. Phys.C74. 49-55 (1997)

[Publications] The OPAL Collaboration: "Production of Fermion-pair Events in e^+e^- Collisions at 161 GeV Centre-of-wass Energy" Phys. Lett.B391. 221-234 (1997)

[Publications] The OPAL Collabration: "Photonic Events with Large Missing Energy in e^+e^- Collisions at √<S>=161 GeV" Phys. Lett.B391. 210-220 (1997)

[Publications] The OPAL Collaboration: "Analysis of Hadronic Final States and the Photon Structure Function F^r_2 in Deep Inelastic Electron-Photon Scattering at LEP" Z. Phys.C74. 33-48 (1997)

[Publications] The OPAL Collaboration: "Search for the Standard Moded Higgs Boson in e^+e^- Collisions at √<S>=161 GeV" Phys. Lett.B393. 231-244 (1997)

[Publications] The OPAL Collaboration: "A Mesurement of Vcb Using B^0→D^*+l^-rl Decays" Phys. Lett.B395. 128-140 (1997)

[Publications] The OPAL Collaboration: "An Improved Measurement of Rb Using a Double Tagging Method" Z. Phys.C74. 1-17 (1997)

[Publications] The OPAL Collaboration: "Measurement of the Semireptonic Branching Fraction of Inclusive b Baryon Decays to Λ" Z. Phys.C74. 423-435 (1997)

[Publications] The OPAL Collaboration: "Search for Charged Scalar Leptons Using the OPAL Detector at √<S>=161 GeV" Phys. Lett.B396. 301-314 (1997)

[Publications] The OPAL Collaboration: "Search for CP Violation in Z^0→τ^+τ^- and an Upper Limit on the Weak Dipole Moment o the τ Lepton" Z. Phys.C74. 403-412 (1997)

[Publications] The OPAL Collaboration: "B^* Production in Z^0 Decays" Z. Phys.C74. 413-422 (1997)

[Publications] The OPAL Collaboration: "Measurement of the Triple Gauge Boson Coupling αwφ from W^+W^- Production in e^+e^- Collisions at √<S>=161GeV" Phys. Lett.B397. 147-157 (1997)

[Publications] The OPAL Collaboration: "Measurement of the b Quark Forward-backward Asymmetry around the Z^0 Reak Using Jet Charge and Vertex Charge" Z. Phys.C75. 385-396 (1997)

[Publications] The OPAL Collaboration: "Study of φ (1020), D^*^± and B^* Spin Alnment in Hadronic Z^0 Decays" Z. Phys.C74. 437-449 (1997)

[Publications] The OPAL Collaboration: "QCD Studies with e^+e^- Annihilation Data at 161GeV" Z. Phys.C75. 193-207 (1997)

[Publications] The OPAL Collaboration: "A Measurement of the Hadronic Decay Current and the Vr-helicity in T^-→π^-π^-π^-Vr" Z. Phys.C75. 593-605 (1997)

[Publications] The OPAL Collaboration: "Production of D-Wave Charm and Charm-Strange Mesons in Hadronic Z^0 Decays" Z. Phys.C76. 425-440 (1997)

[Publications] The OPAL Collaboration: "A Study of B Meson Oscillations Using Hadronic Z^0 Decays Containing Leptons" Z. Phys.C76. 401-415 (1997)

[Publications] The OPAL Collaboration: "Search for Scalar TOP and Scalar Bottom Quarks at √<S>=170-172 GeV in e^+e^- Collisions" Z. Phys.C75. 409-420 (1997)

[Publications] The OPAL Collaboration: "An Upper Limit on the Branching Ratio for τ Decays into Seven Charged Particles" Phys. Lett.B404. 213-222 (1997)

[Publications] The OPAL Collaboration: "Measurement of the Branching Fractions and Foruard-Backward Asymmetries of the Z^0 of tje Z^0 into Light Quarks" Z. Phys.C76. 387-440 (1997)

[Publications] The OPAL Collaboration: "An Updated Study of B Meson Oscillations using Dilepton Events" Z. Phys.C76. 417-423 (1997)

[Publications] The OPAL Collaboration: "Measurement of the quarlt to photon Fragmentation Function through the Inclusive Production of Prompt Photons in Hadronic Z^0 Decays" Eur. Phys. J.C2. 39-48 (1998)

[Publications] The OPAL Collaboration: "Measurement of the Q^2 Evolution of the Photon Structure Function F^r_2" Phys. Lettt.B414. 387-401 (1997)

[Publications] The OPAL Collaboration: "Measurement of f(c→D^*+X), f(b→D^*+X) and Γcc / Γhad Using D^*^± Mesons" Eur. Phys. J.C1. 439-459 (1998)

[Publications] The OPAL Collaboration: "Spin Alignment of Leading K^* (892)^0 Mesons in Haclronic Z^0 Decays" Phys. Lett.B412. 210-224 (1997)

[Publications] The OPAL Collaboration: "Measurement of the Photon Stucture Function F^r_2 at low X" Phys. Lett.B412. 225-234 (1997)

[Publications] The OPAL Collaboration: "Multiplicity distributions of gluon and quark jets and tests of QCD analytic prediction" Eur. Phys. J.C1. 479-494 (1998)

[Publications] The OPAL Collaboration: "Multi-photon Fmal States in e^+e^- Collisions at √<S>=130-172 GeV" Eur. Phys. J.C1. 21-30 (1998)

[Publications] The OPAL Collaboration: "Search for the Standard Model Higgs Boson in e^+e^- Collisions at √<S>=161-172 GeV" Eur. Phys. J.C1. 425-438 (1998)

[Publications] The OPAL Collaboration: "Measurement of the WBoson Mass and W^+W^- Production and Decay Properties in e^+e^- Collisions at √<S>=172 GeV" Eur. Phys. J.C1. 395-424 (1998)

[Publications] The OPAL Collaboration: "Search for a Massive Di-photon Resonance at √<S>=91-172 GeV" Eur. Phys. J.C1. 31-43 (1998)

[Publications] The OPAL Collaboration: "Search for Unstable Heavy and Excited Leptons in e^+e^- Collisions at √<S>=170-172 GeV" Eur. Phys. J.C1. 45-64 (1998)

小林富雄東京大学, 素粒子物理国際研究センター, 教授 (50126059)

[Publications] The OPAL Collaboration: "Study of φ (1020), D^^± and B^ Spin Alnment in Hadronic Z^0 Decays" Z. Phys.C74. 437-449 (1997)

[Publications] The OPAL Collaboration: "Measurement of f(c→D^+X), f(b→D^+X) and Γcc / Γhad Using D^*^± Mesons" Eur. Phys. J.C1. 439-459 (1998)