Single-particle potential of the $Lambda$ hyperon in nuclear matter with chiral effective field theory NLO interactions including effects of YNN three-baryon interactions
Single-particle potential of the $Lambda$ hyperon in nuclear matter with chiral effective field theory NLO interactions including effects of YNN three-baryon interactions
复制标题
核物质中 $Lambda$ 超子的单粒子势与手性有效场论 NLO 相互作用，包括 YNN 三重子相互作用的影响
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发表时间：
2018
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通讯作者：
M. Kohno
中科院分区：
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作者：
M. Kohno
采用手性有效场论中参数化的超子-核子和超子-核子-核子相互作用，在最低阶Bruckner理论的框架下，在对称核物质和纯中子物质中计算了$Lambda$和$Sigma$超子的单粒子势。手性NLO相互作用具有强的$Lambda$N-$Sigma$N耦合。虽然如果耦合被关闭，$Lambda$势是排斥的，但$Lambda$N-$Sigma$N相关带来了与经验数据一致的吸引力。Sigma势是排斥的，这也与经验信息一致。有趣的结果是，$Lambda$势变得比正常密度更浅。这提供了在不引入特别假设的情况下解决超子难题的可能性。考虑了$Lambda$NN-$Lambda$NN和$Lambda$NN-$Sigma$NN三重子力的影响。这些三重子力首先被简化为核物质中正常有序的有效两重子相互作用，然后被纳入$G$矩阵方程。$Lambda$NN-$Lambda$NN相互作用的斥力在正常密度下为5 MeV数量级，并且随着密度的增加而增大。$Lambda$NN-$Sigma$NN耦合的效应补偿了正常密度下的斥力。在较高密度下，三重子相互作用对λ单粒子势的净效应是排斥的。
Adopting hyperon-nucleon and hyperon-nucleon-nucleon interactions parametrized in chiral effective field theory, single-particle potentials of the $Lambda$ and $Sigma$ hyperons are evaluated in symmetric nuclear matter and in pure neutron matter within the framework of lowest order Bruckner theory. The chiral NLO interaction bears strong $Lambda$N-$Sigma$N coupling. Although the $Lambda$ potential is repulsive if the coupling is switched off, the $Lambda$N-$Sigma$N correlation brings about the attraction consistent with empirical data. The $Sigma$ potential is repulsive, which is also consistent with empirical information. The interesting result is that the $Lambda$ potential becomes shallower beyond normal density. This provides the possibility to solve the hyperon puzzle without introducing ad hoc assumptions. The effects of the $Lambda$NN-$Lambda$NN and $Lambda$NN-$Sigma$NN three-baryon forces are considered. These three-baryon forces are first reduced to normal-ordered effective two-baryon interactions in nuclear matter and then incorporated in the $G$-matrix equation. The repulsion from the $Lambda$NN-$Lambda$NN interaction is of the order of 5 MeV at the normal density, and becomes larger with increasing the density. The effects of the $Lambda$NN-$Sigma$NN coupling compensate the repulsion at normal density. The net effect of the three-baryon interactions to the $Lambda$ single-particle potential is repulsive at higher densities.