The nuclear symmetry energy (E_sym(\roh)) is a vital ingredient of our understanding of many processes, from heavy-ion collisions to neutron stars structure. While the total nuclear symmetry energy at nuclear saturation density (ρ_0) is relatively well determined, its value at supranuclear densities is not. The latter can be better constrained by separately examining its kinetic and potential terms and their density dependencies. The kinetic term of the symmetry energy, E_sym^kin(ρ_0), equals the difference in the per-nucleon kinetic energy between pure neutron matter (PNM) and symmetric nuclear matter (SNM), often calculated using a simple Fermi gas model. However, experiments show that tensor force induced short-range correlations (SRC) between proton-neutron pairs shift nucleons to high-momentum in SNM, but have almost no effect in PNM. We present an approximate analytical expression for E_sym^kin(ρ) of correlated nucleonic matter. In our model, E_sym^kin(ρ_0) = -10 MeV, which differs significantly from +12.5 MeV for the widely-used free Fermi gas model. This result is consistent with our analysis of recent data on the free proton-to-neutron ratios measured in intermediate energy nucleus-nucleus collisions as well as with microscopic many-body calculations, and previous phenomenological extractions. We then use our calculated E_sym^kin(ρ) in combination with the known total symmetry energy and its density dependence at saturation density to constrain the value and density dependence of the potential part and to extrapolate the total symmetry energy to supranuclear densities.
Symmetry energy of cold nucleonic matter within a relativistic mean field model encapsulating effects of high momentum nucleons induced by short-range correlations
Mean free paths and in-medium scattering cross sections of energetic nucleons in neutron-rich nucleonic matter within the relativistic impulse approximation
Ruling out nucleonic direct Urca cooling in low-mass neutron stars using nuclear data
Université de Caen Normandie, ENSICAEN, CNRS/IN2P3, LPC Caen UMR6534（卡昂诺曼底大学，ENSICAEN，CNRS/IN2P3，LPC Caen UMR6534）；Dipartimento di Fisica “Aldo Pontremoli”, Università degli Studi di Milano（米兰大学物理系“Aldo Pontremoli”）；INFN, Sezione di Milano（意大利国家核物理研究所，米兰分部）；Department of Physics, University of Houston（休斯顿大学物理系）；Grand Accélérateur National d’Ions Lourds (GANIL), CEA/DRF-CNRS/IN2P3（重离子国家大型加速器（GANIL），CEA/DRF-CNRS/IN2P3）
Bayesian Inference of High-density Nuclear Symmetry Energy from Radii of Canonical Neutron Stars
质量为1.4 M $_{\odot}$的中子星的半径$R_{1.4}$在最近的许多研究文献中一直被提取。利用具有代表性的$R_{1.4}$数据，我们推导出高密度核对称能$E_{\rm{sym}}(ρ)$和相关的核子比能$E_0(ρ)$在对称核物质（SNM）内的贝叶斯统计方法使用显式的同位旋依赖的参数状态方程（EOS）的核子物质。我们发现：（1）现有的天体物理数据已经可以大大提高我们目前对$ρ_0-2.5ρ_0$密度范围内物态方程的认识。特别地，在68%的置信水平下，在核物质饱和密度$ρ_0$的两倍处的对称能被确定为$E_{\mathrm{sym}}(2ρ_0)$ =39.2 $_{-8.2}^{+12.1}$ MeV。(2)精确测量的$R_{1.4}$单独与4\% 1 $σ$的统计误差，但没有系统误差将不会改善太多的约束条件的状态方程的致密丰中子核子物质相比，我们从使用现有的半径数据提取。(3)$R_{1.4}$半径数据和其他一般条件，如观测到的NS最大质量和因果关系条件，为高阶EOS参数引入了强相关性。因此，推断出的$E_{\rm{sym}}(ρ)$的高密度行为强烈地依赖于如何参数化高密度SNM EOS $E_0(ρ)$，反之亦然。(4)观察到的最大NS质量的值以及它是否被用作最小最大质量的锐截止值或通过高斯分布显著影响$E_0(ρ)$和$E_{\rm{sym}}(ρ)$两者的下…
Constraining the neutron-proton effective mass splitting using empirical constraints on the density dependence of nuclear symmetry energy around normal density
