同位旋非对称核物质性质与扩展的BHF方法(Ⅱ)状态方程、对称能以及三体核力效应

Properties of Isospin Asymmetric Nuclear Matter and Extended Brueckner-Hartree-Fock Approach (Ⅱ) Equation of State,Symmetry Energy and Three-Body Force Effects

在同位旋相关的BHF理论框架内 ,研究了微观三体核力对非对称核物质状态方程和原子核对称能的影响 .结果表明 :即使引进了微观三体核力后 ,核物质结合能随同位旋非对称度的变化关系仍然能够在整个同位旋自由度范围内(0≤β≤ 1) 相当精确地满足二次方规律 .在核物质饱和密度 ρ0 =0 .17fm- 3处 ,三体核力对于对称能Esym的影响很小 ,考虑三体核力后得到的对称能为 30 .71MeV ,与其经验值符合得很好 ;对于高密度核物质 ,由于三体核力效应 ,对称能明显增大 ,而且三体核力使对称能随密度的增大要比不考虑三体核力情况下的计算结果陡得多 .同时还给出了对称能的密度依赖关系的一个简单的参数化形式 .

Within the isospin dependent Brueckner-Hartree-Fock approach,the equation of state of isospin asymmetric nuclear matter and its isospin dependence have been investigated in the whole isospin range. The present work has been focused on the effects of a microscopic three-body force on the equation of state of asymmetric nuclear matter and nuclear symmetry energy. It is shown that,even with the presence of the three-body force,the empirical parabolic law of the energy per nucleon vs isospin asymmetry is still fulfilled accurately in the whole isospin range (0≤ β ≤1). Around the empirical saturation density ρ 0=0.17 fm -3,the three-body force effect on the symmetry energy is rather small and the symmetry energy at the saturation density obtained in the presence of the three-body force is 30.71MeV in good agreement with its empirical value 30±4MeV;while at high density,the three-body force provides a strong enhancement of the symmetry energy and makes the symmetry energy increase much more rapid as increasing density. A simple parametrization of the symmetry energy as a function of density is proposed = =