In this work, we extend the two-flavor Nambu–Jona-Lasinio model to one capable of exploring quark and nuclear matter consistently. With an extra term standing for quark-nucleon interactions, nucleons could automatically emerge as color-singlet three-quark entities by following a process similar to mesons. Besides the quark part in mean field approximation, both mesons and nucleons could contribute to the thermodynamic potential thus possibly give rise to quarkyonic matter beyond mean field. In the study, two kinds of “confining” couplings are adopted for the new interaction term and two different quark masses are considered for comparison. It turns out that only confined nuclear matter or deconfined quark matter is possible for all the cases at zero temperature, thus quarkyonic matter is not favored at all. Even more strictly, only the case with stronger confinement effect and a smaller quark mass admits a physical first-order phase transition from nuclear matter to quark matter around twice saturation density.

中文翻译：

---

夸克和核物质的扩展 Nambu-Jona-Lasinio 模型


在这项工作中，我们将两种风格的 Nambu-Jona-Lasinio 模型扩展到能够一致地探索夸克和核物质的模型。夸克-核子相互作用（quark-nucleon interactions）是一个额外的术语，核子可以通过遵循类似于介子的过程自动成为彩色单重态三夸克实体。除了平均场近似中的夸克部分外，介子和核子都可能对热力学势做出贡献，因此可能会产生超出平均场的夸克物质。在该研究中，新的交互项采用了两种“限制”耦合，并考虑了两种不同的夸克质量进行比较。事实证明，在零温度下，所有情况下只有受限核物质或非受限夸克物质是可能的，因此根本不看好夸克物质。更严格地说，只有具有更强约束效应和较小夸克质量的情况才允许从核物质到夸克物质的物理一阶相变大约是饱和密度的两倍。