Study of Elementary Particles Using OPAL Detector at LEP-II

使用 LEP-II OPAL 探测器进行基本粒子研究

• 批准号: 09044060
• 负责人: KOBAYASHI Tomio
• 金额: $ 11.78万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for international Scientific Research
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09044060/
• 关键词: CERN; LEP-II; OPAL experiment; Leadglass calorimeter; Standard Model; W boson; Higgs boson; Supersymmetry; ヒッグス粒子

The world highest energy e^+e^- collider LEP at CERN has started its operation in 1989. After completion in 1995 of highly successful physics program at the Z resonance, LEP has started the energy upgrade program LEP2 in. 1996, exceeding the collision energy sufficient to produce the W boson in pair. In 1997 the LEP collision energy was increased to 183 GeV and further pushed up to 189 0eV in 1998. The OPAL experiment, in which we have been playing a leading role, has successfully collected data at this new energy region. In order to make full use of these data, we worked on understanding the detector performance at high energy, precise calibration of the detector, developments for improved physics analysis technique to gain precision of measurements and sensitivity for searches, and we also pursued a number of new physics topics.1. About 4000 W pairs events have been collected. The production cross-section, total W width and decay branching ratios were precisely measured. Accurate measurement of the W mass, together with the precision results of the Z boson, provides information for crucial tests of the Standard Model. Based on the increased data sample of W pair events, precision of W mass determination has been largely improved.2. Systematic investigations were made for varieties of Standard Model processes such as fermion pair production, Z pair production, single W production and general four-fermion final states. The Standard Model is found to work well at this higher energy region.3. The mass of the Higgs boson, which is a key element of the Standard Model yet undetected, is found to be heavier than about 91 GeV.4. Searches for Supersymmetric particles were performed and improved limits on the parameters in the theory have been obtained.

欧洲核子研究中心的世界最高能量e^+e^-对撞机LEP已于1989年开始运行。在1995年完成了非常成功的Z共振物理计划后，LEP已经开始了能源升级计划LEP2。1996年，超过了足以产生成对W玻色子的碰撞能量。1997年LEP碰撞能增加到183GeV，1998年进一步提高到1890 eV。我们一直在发挥主导作用的欧泊实验已经成功地在这一新能源区域收集了数据。为了充分利用这些数据，我们致力于了解探测器在高能下的性能，探测器的精确校准，改进物理分析技术以获得测量精度和搜索灵敏度的发展，我们还研究了一些新的物理主题1。已收集到约4000个W对事件。精确测量了产生截面、全W宽和衰变分支比。W质量的精确测量，以及Z玻色子的精确结果，为标准模型的关键测试提供了信息。基于增加的W对事件的数据样本，W质量测定的精度有了很大的提高。系统地研究了各种标准模型过程，如费米子对产生、Z对产生、单W产生和一般的四个费米子末态。标准模型被发现在这一较高能量区域工作得很好。希格斯玻色子的质量被发现比大约91GeV.4重。希格斯玻色子是标准模型中尚未被探测到的关键元素。对超对称粒子进行了搜索，得到了理论中参数的改进极限。

项目成果

The OPAL Collaboration: "Search for Acoplanar Lepton Pair Events in e^+e^- Annihilation at √<S>=161, 172, and 183 GeV" CERN-EP/98-122 Submitted to Euro. Phys. Journal.

OPAL 合作：“搜索 e^+e^- √<S>=161、172 和 183 GeV 处的无共面轻子对事件”CERN-EP/98-122 提交给《欧洲物理学杂志》。

The OPAL Collaboration: "Bose-Einstein Correlations in e^+e^-→W^+W^- at 172 and 183 GeV" CERN-EP/98-174 (Submitted to Euro. ?Phys. Journal).

OPAL 合作：“172 和 183 GeV 处 e^+e^-→W^+W^- 中的 Bose-Einstein 相关性”CERN-EP/98-174（提交给 Euro.Phys.Journal）。

The OPAL Collaboration, K.Ackerstaff et al.: "Measurements of the b Quark Forward-backward Asymmetry around the Z^0 Peak Using Jet Charge and Vertex Charge" Zeit.fur Physik. C75. 385-396 (1997)

OPAL 合作，K.Ackerstaff 等人：“使用射流电荷和顶点电荷测量 Z^0 峰周围的 b 夸克前后不对称性”Zeit.fur Physik。

The OPAL Collaboration, K.Ackerstaff et al.: "An Updated Study of B Meson Oscillations using Dilepton Events" Zeit.fur Physik. C76. 417-423 (1997)

OPAL 合作，K.Ackerstaff 等人：“使用 Dilepton 事件对 B 介子振荡的更新研究”Zeit.fur Physik。

The OPAL Collaboration, K.Ackerstaff et al.: "Polarization and Forward-Backward Asymmetry of LAMBDA Baryons in Hadronic Z^0 Decays" Euro.Phys.Journal. C2. 49-59 (1998)

OPAL 合作，K.Ackerstaff 等人：“强子 Z^0 衰变中 LAMBDA 重子的极化和前后不对称”Euro.Phys.Journal。