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arXiv 1509.09290nucl-thastro-ph.SRnucl-ex
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相对论平均场模型中冷核子物质的对称性能量

Symmetry energy of cold nucleonic matter within a relativistic mean field model encapsulating effects of high momentum nucleons induced by short-range correlations

Bao-Jun Cai, Bao-An Li

摘要:

近年来,利用实验数据和微观模型计算,对描述富中子核子物质中短程关联修正的单核子动量分布的同位旋相关参数进行了约束,并取得了重要进展。利用非线性相对论平均场模型中的约束单核子动量分布,研究了非对称核子物质的物态方程,特别是核对称能$E_{\rm{sym}}(ρ)$的密度依赖性.首先,作为模型的检验,最近从电子-核散射实验中提取的平均核子动能,使用中子-质子主导模型是很好地再现RMF模型纳入SRC诱导的高动量核子的影响,而它是显着低于预测的RMF模型使用一个台阶函数的单核子动量分布的自由费米气体(FFG)模型。其次,在核物质饱和密度$ρ_0=0.16\,\rm{fm}^{-3}$下,得到准核子的动能对称能为$E^{\rm{kin}}_{\rm{sym}}(ρ_0)=-16.94\pm13.66\,\rm{MeV}$,这与FFG模型对$E^{\rm{kin}}_{\rm{sym}}(ρ_0)\approx 12.5$ MeV的预测有很大的不同.第三,比较了在$ρ_0$上用两组完全相同的模型参数对对称核物质状态方程和对称核物质对称能的经验约束条件进行的有和无高动量核子的RMF计算,SRC修正的单核子动量分布被发现使$E_{\rm{sym}}(ρ)$在$ρ_0$周围更凹,这是通过在亚饱和和超饱和下显著地软化它来实现的。饱和密度,从而导致与现有的实验数据更好地协议的同位旋相关的不可压缩性ANM。

英文摘要:

Significant progress has been made recently in constraining the isospin-dependent parameters characterizing the SRC (short-range correlation)-modified single-nucleon momentum distribution in neutron-rich nucleonic matter using both experimental data and microscopic model calculations. Using the constrained single-nucleon momentum distribution in a nonlinear relativistic mean field (RMF) model, we study the equation of state (EOS) of asymmetric nucleonic matter (ANM), especially the density dependence of nuclear symmetry energy $E_{\rm{sym}}(ρ)$. Firstly, as a test of the model, the average nucleon kinetic energy extracted recently from electron-nucleus scattering experiments using a neutron-proton dominance model is well reproduced by the RMF model incorporating effects of the SRC-induced high momentum nucleons, while it is significantly under predicted by the RMF model using a step function for the single-nucleon momentum distribution as in free Fermi gas (FFG) models. Secondly, the kinetic symmetry energy of quasi-nucleons is found to be $E^{\rm{kin}}_{\rm{sym}}(ρ_0)=-16.94\pm13.66\,\rm{MeV}$ which is dramatically different from the prediction of $E^{\rm{kin}}_{\rm{sym}}(ρ_0)\approx 12.5$ MeV by FFG models at nuclear matter saturation density $ρ_0=0.16\,\rm{fm}^{-3}$. Thirdly, comparing the RMF calculations with and without the high momentum nucleons using two sets of model parameters both reproducing identically all empirically constraints on the EOS of symmetric nuclear matter (SNM) and the symmetry energy of ANM at $ρ_0$, the SRC-modified single-nucleon momentum distribution is found to make the $E_{\rm{sym}}(ρ)$ more concave around $ρ_0$ by softening it significantly at both sub-saturation and supra-saturation densities, leading to an isospin-dependent incompressibility of ANM in better agreement with existing experimental data.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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