Low-Density Neutron Matter and the Unitary Limit
Low-Density Neutron Matter and the Unitary Limit
复制标题
低密度中子物质和单一极限
DOI：
10.3389/fphy.2021.660622
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
I. Vidaña
中科院分区：
文献类型：
--
作者：
I. Vidaña
我们回顾了低密度区域中子物质的性质。特别是，我们修改了其基态能量和超流中子配对间隙，并分析了它们从弱耦合状态到强耦合状态的演化。能量和配对间隙的计算分别在核物质的 Brueckner-Hartree-Fock (BHF) 方法和 Bardeen-Cooper-Schrieffer (BCS) 理论中使用 Entem 和 Machleidt 在 N3LO 处的手性核子-核子相互作用和阿贡 V18 唯象势进行。还显示了简单高斯势的能量结果，其强度和范围经过调整以再现 1S0 中子-中子散射长度和有效范围。我们的结果与中子物质和冷原子的量子蒙特卡罗（QMC）计算结果进行了比较。还计算了中子物质中的 Tan 接触参数，发现与仅在非常低密度的超冷原子的实验数据相当一致。我们发现低密度中子物质在单一极限下表现出接近费米气体的行为，尽管实际上从未达到这个极限。我们还回顾了作者在最近的一项工作中研究过的浸没在低密度自由自旋中子费米气体中的自旋向下中子杂质的性质（能量、有效质量和准粒子残留），其中表明这些性质非常接近酉极限下有吸引力的费米极化子的性质。
We review the properties of neutron matter in the low-density regime. In particular, we revise its ground state energy and the superfluid neutron pairing gap and analyze their evolution from the weak to the strong coupling regime. The calculations of the energy and the pairing gap are performed, respectively, within the Brueckner–Hartree–Fock (BHF) approach of nuclear matter and the Bardeen–Cooper–Schrieffer (BCS) theory using the chiral nucleon-nucleon interaction of Entem and Machleidt at N3LO and the Argonne V18 phenomenological potential. Results for the energy are also shown for a simple Gaussian potential with a strength and range adjusted to reproduce the 1S0 neutron-neutron scattering length and effective range. Our results are compared with those of quantum Monte Carlo (QMC) calculations for neutron matter and cold atoms. The Tan contact parameter in neutron matter is also calculated, finding a reasonable agreement with experimental data from ultra-cold atoms only at very low densities. We find that low-density neutron matter exhibits a behavior close to that of a Fermi gas at the unitary limit, although, this limit is actually never reached. We also review the properties (energy, effective mass, and quasiparticle residue) of a spin-down neutron impurity immersed in a low-density free Fermi gas of spin-up neutrons already studied by the author in a recent work where it was shown that these properties are very close to those of an attractive Fermi polaron in the unitary limit.
影响因子：
8.6
作者：
I. Tews;T. Krüger;K. Hebeler;A. Schwenk
通讯作者：
I. Tews;T. Krüger;K. Hebeler;A. Schwenk