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Study of the Electroweak Int. with High Energy e-p Collision

弱电国际研究。

基本信息

批准号：
08044059
负责人：
YAMADA Sakue
金额：
$ 5.76万
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：
1996
资助国家：
日本
起止时间：
1996 至无数据
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08044059/
关键词：
electron-proton collision electroweak interaction standard model quantum chromodynamics neutral current interaction leptoquarks proton structure functions charged current interaction HERA ZEUS W、Z粒子

项目摘要

We studied the electroweak interaction in electron-proton collisions by using a multi purpose detector built in an international collaboration (ZEUS) at DESY in Germany. The unique collider HERA provides high-energy electron-proton collison, whose maximum four momentum transfer squared (QィイD12ィエD1) reaches 10ィイD15ィエD1 GeVィイD12ィエD1. By investigating the neutral current (NC) interaction which is mediated by the photon and/or the Z boson as well as the charged current (CC) interaction mediated by the W boson, we could test the various aspects of the standard model.Precise measurements of the NC interaction were performed in a wide QィイD12ィエD1 range from 0.5GeVィイD12ィエD1 to 5000GeVィイD12ィエD1 in order to determine the proton structure functions. The results were well fitted with models based with the quantum chromodynamics. Charged ciurrent cross sections were measured with data taken in the previous years. The results were consistent with the prediction of the standard models The mass of W boson was extracted from the data to be consistent with that obtained by direct measurements. The analysis for the NC using full data showed an excess from the standard model prediction in the very high QィイD12ィエD1 region. Is is not yet excluded that this is due to a statistical fluctuation but it might be an effect of new particles such as leptoquarks. re-analysis on the CC cross sections was quickly performed by using the full data. Preliminary results were shown in a conference in June 1996. There was a tendency that the data were above the standard model prediction, although it is not yet conclusive due to lack of statistics and more ambiguity in the model prediction compared with the NC cross section.We need more data in order to confirm the effect. HERA machine upgrade foreseen in year 2000 will give us this opportunity.

利用德国DESY国际合作组（ZEUS）研制的多用途探测器，研究了电子-质子碰撞中的电弱相互作用。独特的对撞机HERA提供高能电子-质子碰撞，其最大四个动量转移平方（Q D 12 D 1）达到10 D 15 D 1 GeV D 12 D 1。通过研究光子和/或Z玻色子介导的中性流（NC）相互作用以及W玻色子介导的带电流（CC）相互作用，我们可以测试标准模型的各个方面。NC相互作用的精确测量是在从0.5GeV的Q12-D12-D1到5000 GeV的Q12-D12-D1的宽范围内进行的，以便确定质子结构函数。结果与基于量子色动力学的模型吻合较好。用前几年的数据测量了电流截面。结果与标准模型的预测一致。从数据中提取的W玻色子质量与直接测量结果一致。使用完整数据对NC进行的分析显示，在非常高的QイD12 D1区域，超出了标准模型的预测。目前还不能排除这是由于统计涨落造成的，但它可能是新粒子（如细夸克）的影响。通过使用完整的数据，对CC横截面进行了快速的重新分析。1996年6月的一次会议上展示了初步成果。有一种趋势是，数据高于标准模型预测，但由于缺乏统计数据，模型预测与NC截面相比更加模糊，因此尚未得出结论。我们需要更多的数据来确认效果。预计2000年HERA机器的升级将给我们提供这个机会。