1996 Fiscal Year Annual Research Report

電子陽電子衝突装置LEP及びLEP-IIでのOPAL測定器による素粒子の研究

Research Project

Project/Area Number	06044046
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)	ROLF DieterH CERN, 素粒子実験部門, 主任研究員大森恒彦高エネルギー物理学研究所, 物理研究部, 助手 (80185389) 神前純一高エネルギー物理学研究所, 物理研究部, 助手 (60169787) 吉村浩司東京大学, 素粒子物理国際研究センター, 助手 (50272464) 森井政宏東京大学, 素粒子物理国際研究センター, 助手 (50242095) 森俊則東京大学, 素粒子物理国際研究センター, 助教授 (90220011) 真下哲郎東京大学, 素粒子物理国際研究センター, 助手 (60181640) 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, 大学院・理学系研究科, 教授 (10092173)
Keywords	LEP / Wボソン / OPAL / 鉛ガラスカロリメーター / 標準理論 / ヒッグスボソン / 超対称性理論 / LEP-II
Research Abstract	電子陽電子衝突装置「LEP」は平成8年度には更にエネルギーを増強して、遂にWボソン生成の敷居値を越えた。春から夏にはWボソンの対生成ギリギリのエネルギー161GeV(1GeV=10億電子ボルト)で運転を行い、9月には超電導加速空洞を更にに増強して、10月〜11月には172GeVにエネルギーを上げて運転した。東京大学が主導的役割を果たしながら進めてきた国際協同実験「OPAL」では、東京大学が受け持つ鉛ガラスカロリメーターが、高性能を維持しつつ働き、データ解析に於いて必須の役割を演じている。東京大学のグループは「OPAL」実験の最も重要な解析全てに主導的役割を果たしている。平成8年度の主な研究成果としては、 (1)Wボソンの質量を161GeVでの生成断面積の測定と、 172GeVにおける質量の直接測定という2つの独立な方法で測定した。まだLEP-IIが始まったばかりでLEP全体でもWボソンの数はわずか数百であるが、陽子-反陽子加速器などで今までに測定された結果と同じ程度の測定精度が既に得られている。 (2)標準理論のミッシングリンクであるヒッグスボソンの探索を行い、その質量下限68.8GeVを出した。又、標準理論を越える理論の中で最も有望な超対称性理論で予言される粒子群の探索も精力的に行い、最も厳しい制限をこの理論に対して与えた。特にWボソンや荷電ヒッグスボソンの超対称性パートナーに対する質量の制限から、グルイ-ノなどのより重い粒子に対しても最も厳しい制限を与えた。これらの結果は、逐次国際会議等で発表され、学術専門誌にも投稿されている。いよいよLEP-IIもエネルギーが上がり、いよいよヒッグス粒子や超対称性粒子が発見される可能性が高い領域であり、今後が期待される。

Research Products

(28 results)

All Other

All Publications (28 results)

[Publications] The OPAL Collaboration G.Alexander et al.: "Search for Chargino and Neutralino Production Using the OPAL Detector at sqrt.s=130-136 GeV at LEP" Physics Letters. B377. 181-194 (1996)
[Publications] LEP Experiments:ALEPH,DELPHI,L3,OPAL: "Combining Heavy Flavour Electroweak Measurements at LEP" Nuclear Inst.and Methods in Physics Research. A378. 101-115 (1996)
[Publications] The OPAL Collaboration G.Alexander et al.: "Improved Measurement of the Lifetime of the tau Lepton" Physics Letters. B374. 341-350 (1996)
[Publications] The OPAL Collaboration G.Alexander et al.: "Topological Search for the Production of Neutralinos and Scalar Particles" Physics Letters. B377. 273-288 (1996)
[Publications] The OPAL Collaboration G.Alexander et al.: "Measurements of Cross-sections and Asymmetries in e+e-Collisions at 130-140 GeV Centre-of-mass Energy" Physics Letters. B376. 232-244 (1996)
[Publications] The OPAL Collaboration G.Alexander et al.: "A Study of Four-Fermion Final States with High Multiplicity at LEP" Physics Letters. B376. 315-328 (1996)
[Publications] The OPAL Collaboration G.Alexander et al.: "Measurements with Photonic Events in e+e- Collisions at Centre-of-Mass Energies of 130-140 GeV" Physics Letters. B377. 222-234 (1996)
[Publications] The OPAL Collaboration G.Alexander et al.: "Upper Limit on the nu_- tau Mass from tau->3h nu_- tau Decays" Zeit fuer Physik. C72. 231-238 (1996)
[Publications] The OPAL Collaboration G.Alexander et al.: "QCD Studies with e+e-Annihilation Data at 130 and 136 GeV" Zeit fuer Physik. C72. 191-206 (1996)
[Publications] The OPAL Collaboration G.Alexander et al.: "A Study of Charm Hadron Production in ZO->cc (bar) and Z0->bb (bar) decays at LEP" Zeit fuer Physik. C72. 1-16 (1996)
[Publications] The OPAL Collaboration G.Alexander et al.: "Prompt J/psi Production in Hadronic Z0 Decays" Physics Letters. B384. 343-352 (1996)
[Publications] The OPAL Collaboration G.Alexander et al.: "A First Measurement of the Lambda (bar) and Lambda Lambda (Lambda (bar) Lambda (bar)) Spin Compositions in Hadronic Z0 Decays" Physics Letters. B384. 377-387 (1996)
[Publications] The OPAL Collaboration G.Alexander et al.: "A Measurement of the B0_- d Oscillatin Frequency Using Leptons and D^*+-Mesons" Zeit fuer Physik. C72. 377-388 (1996)
[Publications] The OPAL Collaboration G.Alexander et al.: "A Precise Measurement of the Tau Polarization and its Forward-Backward Asymmetry at LEP" Zeit fuer Physik. C72. 365-376 (1996)
[Publications] The OPAL Collaboration G.Alexander et al.: "Multiplicity Dependence of Bose-Einstein Correlations in Hadronic Z0 Decays" Zeit fuer Physik. C72. 389-398 (1996)
[Publications] The OPAL Collaboration G.Alexander et al.: "Search for Excited Leptons in e+e-Collisions at sqrt (s)=130 and 136 GeV" Physics Letters. B386. 463-474 (1996)
[Publications] The OPAL Collaboration G.Alexander et al.: "Search for Unstable Neutral and Charged Heavy Leptons in e+e-Collisions at sqrt (s) + 130 and 136 GeV" Physics Letters. B385. 433-444 (1996)
[Publications] The OPAL Collaboration G.Alexander et al.: "Searches for Supersymmetric Particles and Anomalous Four-Jet Production at sqrt (s)=130 and 136 GeV at LEP" Zeit fuer Physik. C73. 201-216 (1997)
[Publications] The OPAL Collaboration G.Alexander et al.: "Test of Four-Fermion Contact Interactin in e+e-Collisions at 130-140 GeV" Physics Letters. B387. 432-442 (1996)
[Publications] The OPAL Collaboration G.Alexander et al.: "Test of QCD analytic predictions for the multiplicity ratio between gluon and quark jets" Physics Letters. B388. 659-672 (1996)
[Publications] The OPAL Collaboration G.Alexander et al.: "Search for Neutral Higgs Bosons in Zo Decays Using the OPAL Detector at LEP" Zeit fuer Physik. C73. 189-199 (1996)
[Publications] The OPAL Collaboration G.Alexander et al.: "Measurement of the Branching Fraction of the Radiative Decay tau-->mu-nu (bar)_- mu nu_- tau gamma" Physics Letters. B388. 437-449 (1996)
[Publications] The OPAL Collaboration K.Ackerstaff et al.: "Search for Scalar Top and Scalar Bottom Quarks Using the OPAL Detector at LEP" Physics Letters. B389. 197-210 (1996)
[Publications] The OPAL Collaboration K.Ackerstaff et al.: "Search for Chargino and Neutralino Production in e+e-Collisions at sqrt (s) =161 GeV" Physics Letters. B389. 616-630 (1996)
[Publications] The OPAL Collaboration K.Ackerstaff et al.: "Search for Excited Leptons in e+e-Collisions at sqrt (s)=161 GeV" Physics Letters. B391. 197-209 (1997)
[Publications] The OPAL Collaboration K.Ackerstaff et al.: "Measurement of the Mass of the W Boson in e+e-Collisions at squrt (s)=161 GeV" Physics Letters. B389. 416 (1996)
[Publications] The OPAL Collaboration K.Ackerstaff et al.: "Production of Fermion-pair Events in e+e-Collisions at 161 GeV Centre-of-mass Energy" Physics Letters. B391. 221-234 (1996)
[Publications] The OPAL Collaboration K.Ackerstaff et al.: "Photonic Events with Large Missing Energy e+e-Collisions at sqrt (s)=161 GeV" Physics Letters. B391. 210-220 (1997)

1996 Fiscal Year Annual Research Report

電子陽電子衝突装置LEP及び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 G.Alexander et al.: "Search for Chargino and Neutralino Production Using the OPAL Detector at sqrt.s=130-136 GeV at LEP" Physics Letters. B377. 181-194 (1996)

[Publications] LEP Experiments:ALEPH,DELPHI,L3,OPAL: "Combining Heavy Flavour Electroweak Measurements at LEP" Nuclear Inst.and Methods in Physics Research. A378. 101-115 (1996)

[Publications] The OPAL Collaboration G.Alexander et al.: "Improved Measurement of the Lifetime of the tau Lepton" Physics Letters. B374. 341-350 (1996)

[Publications] The OPAL Collaboration G.Alexander et al.: "Topological Search for the Production of Neutralinos and Scalar Particles" Physics Letters. B377. 273-288 (1996)

[Publications] The OPAL Collaboration G.Alexander et al.: "Measurements of Cross-sections and Asymmetries in e+e-Collisions at 130-140 GeV Centre-of-mass Energy" Physics Letters. B376. 232-244 (1996)

[Publications] The OPAL Collaboration G.Alexander et al.: "A Study of Four-Fermion Final States with High Multiplicity at LEP" Physics Letters. B376. 315-328 (1996)

[Publications] The OPAL Collaboration G.Alexander et al.: "Measurements with Photonic Events in e+e- Collisions at Centre-of-Mass Energies of 130-140 GeV" Physics Letters. B377. 222-234 (1996)

[Publications] The OPAL Collaboration G.Alexander et al.: "Upper Limit on the nu_- tau Mass from tau->3h nu_- tau Decays" Zeit fuer Physik. C72. 231-238 (1996)

[Publications] The OPAL Collaboration G.Alexander et al.: "QCD Studies with e+e-Annihilation Data at 130 and 136 GeV" Zeit fuer Physik. C72. 191-206 (1996)

[Publications] The OPAL Collaboration G.Alexander et al.: "A Study of Charm Hadron Production in ZO->cc (bar) and Z0->bb (bar) decays at LEP" Zeit fuer Physik. C72. 1-16 (1996)

[Publications] The OPAL Collaboration G.Alexander et al.: "Prompt J/psi Production in Hadronic Z0 Decays" Physics Letters. B384. 343-352 (1996)

[Publications] The OPAL Collaboration G.Alexander et al.: "A First Measurement of the Lambda (bar) and Lambda Lambda (Lambda (bar) Lambda (bar)) Spin Compositions in Hadronic Z0 Decays" Physics Letters. B384. 377-387 (1996)

[Publications] The OPAL Collaboration G.Alexander et al.: "A Measurement of the B0_- d Oscillatin Frequency Using Leptons and D^*+-Mesons" Zeit fuer Physik. C72. 377-388 (1996)

[Publications] The OPAL Collaboration G.Alexander et al.: "A Precise Measurement of the Tau Polarization and its Forward-Backward Asymmetry at LEP" Zeit fuer Physik. C72. 365-376 (1996)

[Publications] The OPAL Collaboration G.Alexander et al.: "Multiplicity Dependence of Bose-Einstein Correlations in Hadronic Z0 Decays" Zeit fuer Physik. C72. 389-398 (1996)

[Publications] The OPAL Collaboration G.Alexander et al.: "Search for Excited Leptons in e+e-Collisions at sqrt (s)=130 and 136 GeV" Physics Letters. B386. 463-474 (1996)

[Publications] The OPAL Collaboration G.Alexander et al.: "Search for Unstable Neutral and Charged Heavy Leptons in e+e-Collisions at sqrt (s) + 130 and 136 GeV" Physics Letters. B385. 433-444 (1996)

[Publications] The OPAL Collaboration G.Alexander et al.: "Searches for Supersymmetric Particles and Anomalous Four-Jet Production at sqrt (s)=130 and 136 GeV at LEP" Zeit fuer Physik. C73. 201-216 (1997)

[Publications] The OPAL Collaboration G.Alexander et al.: "Test of Four-Fermion Contact Interactin in e+e-Collisions at 130-140 GeV" Physics Letters. B387. 432-442 (1996)

[Publications] The OPAL Collaboration G.Alexander et al.: "Test of QCD analytic predictions for the multiplicity ratio between gluon and quark jets" Physics Letters. B388. 659-672 (1996)

[Publications] The OPAL Collaboration G.Alexander et al.: "Search for Neutral Higgs Bosons in Zo Decays Using the OPAL Detector at LEP" Zeit fuer Physik. C73. 189-199 (1996)

[Publications] The OPAL Collaboration G.Alexander et al.: "Measurement of the Branching Fraction of the Radiative Decay tau-->mu-nu (bar)_- mu nu_- tau gamma" Physics Letters. B388. 437-449 (1996)

[Publications] The OPAL Collaboration K.Ackerstaff et al.: "Search for Scalar Top and Scalar Bottom Quarks Using the OPAL Detector at LEP" Physics Letters. B389. 197-210 (1996)

[Publications] The OPAL Collaboration K.Ackerstaff et al.: "Search for Chargino and Neutralino Production in e+e-Collisions at sqrt (s) =161 GeV" Physics Letters. B389. 616-630 (1996)

[Publications] The OPAL Collaboration K.Ackerstaff et al.: "Search for Excited Leptons in e+e-Collisions at sqrt (s)=161 GeV" Physics Letters. B391. 197-209 (1997)

[Publications] The OPAL Collaboration K.Ackerstaff et al.: "Measurement of the Mass of the W Boson in e+e-Collisions at squrt (s)=161 GeV" Physics Letters. B389. 416 (1996)

[Publications] The OPAL Collaboration K.Ackerstaff et al.: "Production of Fermion-pair Events in e+e-Collisions at 161 GeV Centre-of-mass Energy" Physics Letters. B391. 221-234 (1996)

[Publications] The OPAL Collaboration K.Ackerstaff et al.: "Photonic Events with Large Missing Energy e+e-Collisions at sqrt (s)=161 GeV" Physics Letters. B391. 210-220 (1997)

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