We report in this paper a study in terms of the nuclear shell model about the location of the calcium isotopes drip line. The starting point is considering the realistic two-body potential derived by Entem and Machleidt within chiral perturbation theory at next-to-next-to-next-to-leading order (N3LO), as well as a chiral three-body force at next-to-next-to-leading order (N2LO) whose structure and low-energy constants are consistent with the two-body potential. Then we construct the effective single-particle energies and residual interaction needed to diagonalize the shell-model Hamiltonian. The calculated two-neutron separation energies agree nicely with experiment until 56Ca, which is the heaviest isotope whose mass has been measured, and do not show any sign of two-neutron emission until 70Ca. We discuss the role of the choice of the model space in determining the neutron drip line, and also the dependence of the results on the parameters of the shell-model Hamiltonian.

中文翻译：

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钙同位素朝向滴落线的壳模型研究

我们在本文中报告了关于钙同位素滴落线位置的核壳模型研究。起点是考虑 Entem 和 Machleidt 在 next-to-next-to-next-to-lead order (N3LO) 的手征微扰理论中推导出的现实二体势，以及 next-to-next-to-next-to-lead order (N3LO) 的手征三体力-to-next-to-leading order (N2LO) 其结构和低能常数与二体势一致。然后我们构造了对角化壳模型哈密顿量所需的有效单粒子能量和残余相互作用。计算出的双中子分离能在 56Ca 之前与实验非常吻合，这是已测量质量的最重同位素，并且在 70Ca 之前没有显示出任何双中子发射迹象。