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Study of baryon structure and baryon-baryon interaction in a chiral quark model

手性夸克模型中重子结构和重子-重子相互作用的研究

基本信息

批准号：
12640290
负责人：
SHIMIZU Kiyotaka
金额：
$ 1.73万
依托单位：
Sophia University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2003
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12640290/
关键词：
Chiral Quark Model Quark Cluster Model Roper Resonance Di-quark Model Inverse Scattering Method Tensor Force Quark Pauli-Blocking Repulsive Core SU(3)クォーク模型核子間相互作用

项目摘要

First we have investigated the structure of SU(3) octet and decuplet baryons including the s-wave and p-wave excited states employing the chiral quark model. We have found that the relativistic treatment of the kinetic energy term and the inclusion of the goldstone boson exchange potentials are essential in order to explain the spectrum of the Roper, p-wave excited states and ground state baryons simultaneously. Here we have also shown that the relativistic treatment of the potential terms is necessary when the relativistic form of the kinetic energy is employed. In order to solve a three body system, we have used the di-quark like model which can take into account the di-quark correlation due to the strong attractive pion exchange potential. Because of the strong attractive pion exchange potential, the mass of the Roper resonance can be nicely reproduced as the radial excited state of the nucleon.Next, we have investigated the effects of quark degrees of freedom on the baryon-baryon scattering by employing the quark cluster model (QCM). We are mainly interested in the origin of the repulsive core in the quark cluster model, where the non-locality plays the most important role. We have employed the inverse scattering method in order to obtain the equivalent local potential which gives the same on-shell values as those of the original QCM non-local potential. We have found that the smallness of the norm kernel produces the repulsion at low energy region and give an attraction when the energy increases. In terms of the local potential, there appears a strong attractive pocket at short distances with the repulsive core outside. Because of this structure, there appears a resonance at a certain energy where the phase shift changes from negative to positive values.

首先，我们利用手征夸克模型研究了SU（3）八重态和十重态重子的结构，包括s波和p波激发态。我们发现，为了同时解释罗珀、p波激发态和基态重子的谱，动能项的相对论处理和Goldstone玻色子交换势的引入是必不可少的。这里我们还表明，当采用相对论形式的动能时，势项的相对论处理是必要的。为了求解三体系统，我们采用了类双夸克模型，该模型考虑了强吸引π交换势引起的双夸克关联。由于强吸引的π介子交换势，罗珀共振的质量可以很好地再现为核子的径向激发态。其次，我们利用夸克集团模型（QCM）研究了夸克自由度对重子-重子散射的影响。我们主要对夸克团模型中排斥核的起源感兴趣，其中非定域性起着最重要的作用。我们采用了逆散射方法，以获得等效的本地势，它给出了相同的壳层上的原始QCM非本地势的值。我们发现，范数核的小在低能区产生排斥，当能量增加时产生吸引。在局域势方面，在短距离处出现了一个强吸引口袋，排斥核心在外面。由于这种结构，在某一能量处出现共振，其中相移从负值变为正值。