The symmetry energy $\gamma$ parameter of relativistic mean-field models

Abstract

The relativistic mean-field models tested in previous works against nuclear matter experimental values, critical parameters and macroscopic stellar properties are revisited and used in the evaluation of the symmetry energy $\gamma$ parameter obtained in three different ways. We have checked that independent of the choice made to calculate the $\gamma$ values, a trend of linear correlation is observed between $\gamma$ and the symmetry energy ($\mathcal{S}_0$) and a more clear linear relationship is established between $\gamma$ and the slope of the symmetry energy ($L_0$). These results directly contribute to the arising of other linear correlations between $\gamma$ and the neutron star radii of $R_{1.0}$ and $R_{1.4}$, in agreement with recent findings. Finally, we have found that short-range correlations induce two specific parametrizations, namely, IU-FSU and DD-ME$\delta$, simultaneouslycompatible with the neutron star mass constraint of $1.93 < M_{max}/M_\odot < 2.05$ and with the overlap band for the $L_0\times\mathcal{S}_0$ region, to present $\gamma$ in the range of $\gamma=0.25\pm0.05$.