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

首先，我们利用手征夸克模型研究了SU(3)八重态和去跃迁重子的结构，包括S波和p波激发态。我们发现，动能项的相对论处理和Goldstone玻色子交换势的包含对于同时解释ROPER、P波激发态和基态重子的能谱是必不可少的。在这里，我们还表明，当使用动能的相对论形式时，势项的相对论处理是必要的。为了求解三体系统，我们使用了类双夸克模型，该模型考虑了由于具有很强的吸引力的介子交换势而产生的双夸克关联。由于具有很强的引力π介子交换势，Roper共振的质量可以很好地再现为核子的径向激发态。接下来，我们利用夸克团簇模型(QCM)研究了夸克自由度对重子-重子散射的影响。我们主要对夸克团簇模型中排斥核的起源感兴趣，其中非局域性起着最重要的作用。我们利用逆散射方法得到了与原QCM非局域势相同的壳面值的等效局域势。我们发现，范数核的小在低能区产生斥力，并在能量增加时产生引力。在局域势方面，在外边有排斥核的短距离内，出现了一个很强的吸引力口袋。由于这种结构，在一定能量处出现共振，相移从负值变为正值。

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.