Study of spin structure of the proton and the neutron with new experimental technique at HERMES

HERMES 采用新实验技术研究质子和中子的自旋结构

基本信息

批准号：
18340058
负责人：
SHIBATA Toshi-aki
金额：
$ 8.28万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18340058/
关键词：
Spin Quark Proton Neutron Deep Inelastic Scattering Gluon Elementary Particle Electron 陽子スピン核子スピン量子色力学パートン HERMES DESY 漸近的自由性

项目摘要

It was found about 20 years ago by EMC at CERN that the quark spin contribution to the proton spin is small. It is called 'proton spin problem'. The HERMES experiment is an international collaboration from 11 countries to study this problem with unique technical capabilities. Electron or positron beam of DESY-HERA of 27.6 GeV and internal gas targets are used Deep-inelastic scattering of electron off the nucleon is measured. The HERMES detects the scattered electron and also produced hadrons. For the hadron identification, the RICH(ring imaging Cherenkov detector) plays a main role.The HERME started its data-taking in 1995 and the data-taking was completed in July 2007. We have received support by Grant-in-aid continuously for 10 years and this was the last two years. During these two years, we published the result of precision measurement of g1(x) structure functions for proton, neutron and deuteron. Like F2(x) structure function in the unpolarized deep inelastic scattering, g1(x) is the fundamental structure function. We determined the quark spin contribution to the nucleon spin with a good precision using this g1(x).We also published the results of hadronization studied by deep-inelastic scattering. Hadronization is in other words fragmentation. For this we measured the multiplicity which is hadron yield per deep inelastic scattering. The fragmentation function determined in deep inelastic scattering can be compared to the one from electron-positron collider experiments.We published the longitudinal and transverse polarization of produced Lambda particles. It is important to extend the study of baryon spin in a way to include strange quark.Finally, we did theoretical calculation of perturbative QCD for DGLAP evolution equation and analyzed the world data in a consistent way.

大约20年前，EMC在CERN发现了对质子自旋的夸克自旋贡献很小。它称为“质子旋转问题”。爱马仕实验是来自11个国家 /地区的国际合作，可通过独特的技术能力研究这个问题。测量了27.6 GEV的DESY HERA的电子或正电子束，并测量了核子上电子的深弹性散射。爱马仕（Hermes）检测到散落的电子，还产生了哈隆。对于强子识别，Rich The Rich Imaging Cherenkov探测器起着主要作用。HERME于1995年开始数据获取，数据获取于2007年7月。我们已经连续获得了10年的赠款，这是过去两年。在这两年中，我们发表了质子，中子和迪特龙的G1（x）结构函数精确测量的结果。像F2（x）的结构函数中的含量无弹性散射一样，G1（x）是基本结构函数。我们使用此G1（x）确定了对核子自旋的夸克自旋贡献。我们还发布了通过深弹性散射研究的强发化结果。换句话说，强环化是分散的。为此，我们测量了多种弹性散射的多重性，即强子产量。可以将在深度非弹性散射中确定的碎裂函数与电子峰撞机实验中的碎片散射进行比较。我们发表了产生的lambda颗粒的纵向和横向极化。重要的是要以一种包括奇怪的夸克的方式扩展对Baryon旋转的研究。从本文中，我们对DGLAP演化方程进行了扰动QCD的理论计算，并以一致的方式分析了世界数据。