论文标题
基于奇偶校验模型，异常对核和中子星的状态方程的影响
Impacts of anomaly on nuclear and neutron star equation of state based on a parity doublet model
论文作者
论文摘要
我们检查了$ u（1）_a $异常在包括手性变体和不变质量的核子的平均双核模型中的作用。我们的模型通过kobayashi-maskawa-'t \ \，hooft（kmt）的相互作用表示$ u（1）_a $异常。在研究了KMT期限在真空中的作用后，我们讨论了其对国家核方程（EOS）的影响。 $ u（1）_a $异常增加了$η'$和$σ$梅森的质量，并增强了手性对称性的破坏。 $ u（1）_a $ anomaly扩大了手性对称和对称性损坏的真空之间的能量差；反过来，高密度的手性恢复与没有异常的情况相比，EOSS的恢复为EOSS增加了更大的能量密度（通常称为袋子常数），从而导致EOSS较软。包括这些$ u（1）_a $效果，我们更新了先前构建的状态统一方程式，该方程将核能EOS插入$ n_b \ le 2n_0 $（$ n_ {0} = 0.16 \，\ rm {fm^{ - 3}}} $：核饱和度密度）和$ n__ $ n_b \ ge 5n_ $ n _ $ n_b \ 0。统一的EOS面临着对中子恒星质量和半径的观察性约束。与$ U（1）$异常相关的EOSS的软化减少了整体半径，从而放松了对手性不变质量$ M_0 $的限制。包括有吸引力的非线性$ρ$ - $ω$耦合与对称能量中坡度参数的改进估计值，我们的新估计值为$ 400 \，{\ rm mev} \ leq m_0 \ leq m_0 \ leq 700 \ leq 700 \，{\ rm mev} $，比以前的$ $ $ $ $ $ $ me。
We examine the role of the $U(1)_A$ anomaly in a parity doublet model of nucleons which include the chiral variant and invariant masses. Our model expresses the $U(1)_A$ anomaly by the Kobayashi-Maskawa-'t\,Hooft (KMT) interaction in the mesonic sector. After examining the roles of the KMT term in vacuum, we discuss its impacts on nuclear equations of state (EOS). The $U(1)_A$ anomaly increases the masses of the $η'$ and $σ$ mesons and enhances the chiral symmetry breaking. The $U(1)_A$ anomaly enlarges the energy difference between chiral symmetric and symmetry broken vacuum; in turn, the chiral restoration at high density adds a larger energy density (often referred as a bag constant) to EOSs than in the case without the anomaly, leading to softer EOSs. Including these $U(1)_A$ effects, we update the previously constructed unified equations of state that interpolate the nucleonic EOS at $n_B \le 2n_0$ ($n_{0} = 0.16\, \rm{fm^{-3}}$: nuclear saturation density) and quark EOS at $n_B \ge 5n_0$. The unified EOS is confronted with the observational constraints on the masses and radii of neutron stars. The softening of EOSs associated with the $U(1)$ anomaly reduces the overall radii, relaxing the previous constraint on the chiral invariant mass $m_0$. Including the attractive nonlinear $ρ$-$ω$ coupling to improved estimates for the slope parameter in the symmetry energy, our new estimate is $400\,{\rm MeV} \leq m_0 \leq 700\,{\rm MeV}$, with $m_0$ smaller than our previous estimate by $\sim 200$ MeV.
