Searches for exotic particles at HERA

通过ZEUS合作在DESY的电子质子对撞机HERA上进行了新粒子和新现象的研究，在1995财政年度期间，对撞机从5月至11月在总质心能量为300 GeV的条件下进行物理学操作。ZEUS探测器表现良好，记录了约7 pb^的总光度<-1>。目前正在重建数据。与此同时，我们继续对去年获得的数据进行分析，得出以下结果。&lt;**&gt;测量了中性电流反应和带电电流反应的深度非弹性散射截面。在Q^2大于10^4 GeV^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。横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。根据耦合的类型，得到的截止范围在1000 GeV和1800 GeV之间。&lt;**&gt;对激发态费米子进行了系统的搜索。没有发现任何证据，并且在50到250 GeV的质量范围内得到了耦合常数的极限。研究了光反应中硬射流的产生。这一研究对于研究W/Z的强子衰变产生具有重要意义。&lt;**&gt;寻找具有大横动量的硬孤立轻子。它们为外来粒子提供了线索。我们发现了一些与W/Z玻色子的产生和轻子衰变相一致的候选粒子。^ &lt;**&gt;对于深非弹性散射和硬光生，继续对具有大快度间隙的事件进行系统研究。

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.