作者：朱镇宇（厦大）、李昂（厦大/通讯作者）、胡金牛（南开大学）、申虹（南开大学）

单核子的性质在自由空间和核介质中会有所不同，然而大多数核物理模型都是基于类点状核子建立起来的。因此为了更好的描述核物质性质，我们需要能自洽处理核子性质的核物理模型，即从夸克层次出发的模型。

我们的工作尝试结合了已有的两种夸克层次模型——袋模型和势模型。这两种模型区别在于，核子内的夸克分别由袋和谐振子势贡献。而在我们的模型中，核子中的夸克相互作用同时由袋和谐振子势描述。夸克禁闭主要由袋贡献，而势则可以被考虑为夸克间的剩余相互作用。

基于这个新的模型，我们研究了核物质和中子星的一系列性质，并和无袋的模型做了对比。对于核物质，我们发现，袋的引入能降低结合能并增加对称能。而对于中子星物质，袋能极大的影响1.4倍太阳质量的半径。

Abstract: We propose the new quark mean-field bag (QMFB) model by incorporating the bag confinement mechanism in the original quark mean-field model. Nuclear matter and neutron star properties are studied with the QMFB model. For the study of the bag effect, we newly fit 12 parameter sets by reproducing the empirical saturation properties of nuclear matter. Quark confinement is found to be mainly demonstrated by the bag after it is included in the model, instead of the confining potential. For nuclear matter, the bag decreases the binding energy and increases the symmetry energy. For neutron star, the bag affects significantly the radius R of a 1.4M⊙ star, with the maximum mass only slightly modified. The bag also has a large suppression effect on the well-accepted R  vs L dependence, with L the symmetry energy slope at the saturation density.

Zhen-Yu Zhu, Ang Li*, Jin-Niu Hu, Hong Shen

See details in https://arxiv.org/abs/1805.04678

Phys. Rev. C 99, 025804 (2019)