A study on quark-exchange and meson-exchange in nuclear force

本文研究了核力的两种机制--介子交换和夸克交换之间的关系，提出了一个统一这两种机制的混合模型，并将其应用于重子-重子相互作用。详细讨论了产生短程排斥子的矢量介子交换机制问题，发现只有矢量介子空间分量的整体吸引贡献才能加到夸克交换贡献中.我们还发现，标量介子交换和赝标量介子交换的贡献可以简单地相加。在此基础上，我们对夸克集团模型中的重子-重子相互作用进行了半唯象分析。对H-二重子的性质进行了预测，并在H-二重子存在的条件下，在同一框架下研究了核子-H-二重子相互作用。对于统一描述介子和重子的相对论夸克模型，我们选择了Nambu-Jona-Lasinio模型，并首次在平均场近似下研究了重子。阐明了代表手征反常的六费米相互作用在稳定平均场解中的作用。我们进一步求解了作为三夸克系统的重子的相对论性Faddeev方程，并得到了仅在^1So态下夸克-夸克相互作用的简单情形的初步解。扩展到更广泛的互动正在进行中。

The relation between two mechanisms of nuclear force,i.e.the meson exchange and the quark exchange, has been studied and a hybrid model unifying the two mechanisms has been proposed and applied to baryon-baryon interaction. A problem of vector meson exchange mechanism in generating the short-range repukion was examined in detail and it was found that only the overall attractive contribution due to the spatial components of the vector meson should be added to the quark exchange contribution. It was also found that the contributions of scalar and pseudo-scalar meson exchanges could be simply added. Based on this observation,we have made a semi-phenomenological analysis of baryon-baryon interaction in the quark cluster model supplemented by pseudo-scalar meson exchanges. Properties of the H-dibaryon were predicted and, under the condition that it existed, the nucleon-H-dibaryon interaction was also studied in the same framework. As for a relativistic quark model describing mesons and baryons in a unified way, we have chosen the Nambu-Jona-Lasinio model and first studied the baryons in a mean field approximation. The role of the six-Fermi interaction representing the chiral anomaly in stabilizing the mean field solution was clarified. We have proceeded further to solve a relativistic Faddeev equation for the baryon as a three-quark system and have obtained a preliminary solution for a simple case of quark-quark interaction only in ^1So state. The extension to a more general interaction is underway.