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Chiral symmetry on the light-cone and effective models

光锥的手性对称性和有效模型

基本信息

批准号：
15540288
负责人：
YAZAKI Koichi
金额：
$ 1.54万
依托单位：
Tokyo Woman's Christian University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2006
项目状态：
已结题

项目摘要

This project followed the previous one "Models of hadrons on the light-cone" (project no.11640258) supported by the Grant-in-Aid for Scientific Research (Basic Research (C) (2)) for the period 1999-2002, and aimed at clarifying how to describe the spontaneous breakdown of chiral symmetry, which is related to the structure of vacuum in the conventional formulation of field theory, in the light-cone formulation, where the vacuum is known to be trivial, and how it is reflected in effective models.In the conventional formulation, the Nambu-Goldstone (NG) particle, which appears as a result of the symmetry brealing, is generated by a local soft modulation of the symmetry transformation generator, and therefore the connection to the underlying symmetry is transparent. This was not the case in the light-cone formulation. We have clarified the connection by considering the peculiar kinematics of the light-cone coordinate and introducing a non-local modulation of the symmetry operator. Actual construction of the modulated operator was made for the Nambu-Jona-Lasinio (NJL) model, which is considered to be an effective theory of QCD. This work has been published in Physical Review D.Concerning effective models, I have continued the collaboration and used the quark-diquark model, which was derived from a relativistic Faddeev approach to 3-quark system in the NJL model, to study the effect of nuclear medium on the structure functions of the nucleon. The calculation gave a reasonable description of the experimentally observed EMC effect. This work has been published in Nuclear Physics A.

本课题是继“强子在光锥上的模型”之后的又一课题（项目编号：11640258）由科学研究资助金资助（基础研究（C）（2）），旨在阐明如何描述手征对称性的自发破坏，手征对称性与场论传统公式中的真空结构有关，在传统的光锥公式中，由于对称性破裂而出现的Nambu-Goldstone（NG）粒子是由对称变换发生器的局部软调制产生的，因此与潜在对称性的联系是透明的。在光锥制剂中情况并非如此。通过考虑光锥坐标的特殊运动学和引入对称算子的非局域调制，我们已经澄清了这种联系。对被认为是QCD的有效理论的Nambu-Jona-Lasinio（NJL）模型进行了调制算符的实际构造。关于有效模型，我继续合作，并使用夸克-双夸克模型，这是从相对论Faddeev方法在NJL模型中的3-夸克系统，研究核介质对核子结构函数的影响。计算给出了一个合理的描述实验观察到的EMC效应。这项工作已发表在Nuclear Physics A上。