Searches for exotic particles at HERA

在 HERA 中搜索奇异粒子

• 批准号: 05044044
• 负责人: YAMADA Sakue
• 金额: $ 12.8万
• 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: 1993
• 资助国家: 日本
• 起止时间: 1993 至 1995
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-05044044/
• 关键词: HERA; ZEUS; Deep inelastic scattering; exotic particle; excited fermion; contact interaction; W; Z boson; large rapidity gap; hard jet; 励起電子; 励起ニュートリノ; 励起クォーク; 新粒子; 励起レプトン; ポメロン; クォーク・グル-オンの分布密度

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.

在DESYHERA电子-质子对撞机上，通过宙斯合作进行了新粒子和新现象的探索。在1995财政年度，对撞机从5月到11月在总质心能量为300GeV的情况下进行物理操作。Zeus探测器表现良好，记录到的总光度约为7pB^-1。数据现在正在重建中。同时，对到去年为止所获得的数据进行了平行分析，得到了以下结果。对于中性电流反应和带电电流反应，都测量了深度非弹性散射截面。在Q^2大于10^4GeV^2的区域，可以观察到W/Z玻色子质量的影响。通过比较e^-p和e^+p数据，可以分离出u夸克和d夸克的贡献。截面与标准模型的预期一致，从而给出了可能的接触相互作用的上限。根据耦合类型的不同，所获得的截止范围在1000GeV到1800GeV之间。系统地研究了受激费米子。在50~250GeV的质量范围内，没有发现证据，并且得到了耦合常数的限制。这项研究对于研究W/Z产生的强子衰变具有重要意义。我们寻找了具有大横向动量的硬孤立轻子(S)。它们为寻找奇异粒子提供了线索。发现了一些与W/Z玻色子的产生和轻子衰变相一致的候选者。对于深度非弹性散射和硬光产生，对快度差较大的事件继续进行了系统的研究。

项目成果

ZEUS Collaboration M.Derrick et al.: "Measurement of the Proton Structure Function F2 from 1993 HERA Data" to be published in Z.Phys.DESY 94-143.

ZEUS 协作 M.Derrick 等人：“Measurement of the Proton Structure Function F2 from 1993 HERA Data”将在 Z.Phys.DESY 94-143 上发表。

ZEUS Collaboration M.Derrick et al.: "Measurement of the proton structure function F_2 in ep scatteing at HERA" Physics Letters B. 316. 412-426 (1993)

ZEUS 协作 M.Derrick 等人：“HERA ep 散射中质子结构函数 F_2 的测量”Physics Letters B. 316. 412-426 (1993)

ZEUS Collaboration M.Derrick et. al.: "Measurement of deltas from Jet Rates in deeo Inelastic Scattering" Physics Letters B. 363. 201-216 (1995)

ZEUS 合作 M.Derrick 等。

ZEUS Collaboration M.Derrick et al.: "Search for leptoquarks with the ZEUS detector" Physics Letters B. 306. 173-186 (1993)

ZEUS 合作 M.Derrick 等人：“使用 ZEUS 探测器搜索轻夸克”Physics Letters B. 306. 173-186 (1993)

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)

ZEUS 合作 M.Derrick 等。