Relativistic description of BCS–BEC crossover in nuclear matter
Relativistic description of BCS–BEC crossover in nuclear matter
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DOI：
10.1016/j.physletb.2009.11.065
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发表时间：
2009-11
影响因子：
4.4
通讯作者：
B. Sun;H. Toki;J. Meng
中科院分区：
文献类型：
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作者：
B. Sun;H. Toki;J. Meng
在微观相对论对理论下，研究了对称物质和中子物质的双中子空间关联以及S 01对道中的中子库珀对超流性到双中子对玻色-爱因斯坦凝聚（BEC）的交叉.我们在粒子-粒子通道中取裸核子-核子相互作用Bonn-B，在粒子-空穴通道中取相对论平均场方法的有效相互作用PK 1。结果表明，随着密度的减小，中子库珀对波函数的空间结构由BCS型向BEC型不断演化。我们看到，在相对距离相当小的1.5 fm和中子费米动量kFn∈[0.6，1.0] fm−1附近，中子对的概率密度非常集中。然而，从有效化学势和准粒子激发谱来看，没有证据表明在任何密度下中子对会出现真正的BEC态。通过检查密度相关函数，最像玻色-爱因斯坦凝聚态的状态可能出现在kFn <$0.2 fm− 1处。从相干长度和中子库珀对的概率分布以及费米面处中子对能隙与动能的比值可以看出，对于对称核（纯中子）物质，在密度为0.05 fm−1<kFn<0.7（0.75）fm−1的区域，存在BCS-BEC交叉的一些特征。
We study theoretically the di-neutron spatial correlations and the crossover from superfluidity of neutron Cooper pairs in the S01 pairing channel to Bose–Einstein condensation (BEC) of di-neutron pairs for both symmetric and neutron matter in the microscopic relativistic pairing theory. We take the bare nucleon–nucleon interaction Bonn-B in the particle–particle channel and the effective interaction PK1 of the relativistic mean-field approach in the particle–hole channel. It is found that the spatial structure of neutron Cooper pair wave function evolves continuously from BCS-type to BEC-type as density decreases. We see a strong concentration of the probability density revealed for the neutron pairs in the fairly small relative distance around 1.5 fm and the neutron Fermi momentum kFn∈[0.6,1.0] fm−1. However, from the effective chemical potential and the quasiparticle excitation spectrum, there is no evidence for the appearance of a true BEC state of neutron pairs at any density. The most BEC-like state may appear at kFn∼0.2 fm−1by examining the density correlation function. From the coherence length and the probability distribution of neutron Cooper pairs as well as the ratio between the neutron pairing gap and the kinetic energy at the Fermi surface, some features of the BCS–BEC crossover are seen in the density regions, 0.05 fm−1<kFn<0.7(0.75) fm−1, for the symmetric nuclear (pure neutron) matter.