Density-dependent symmetry energy at subsaturation densities from nuclear mass differences

Abstract

We extract the mass-dependent symmetry energy coefficients ${a}_{\mathrm{sym}}(A)$ with the nuclear mass differences reducing the uncertainties as far as possible. The estimated ${a}_{\mathrm{sym}}(A)$ of ${}^{208}\mathrm{Pb}$ is $22.4\ifmmode\pm\else\textpm\fi{}0.3$ MeV, which is further used to analyze the density-dependent nuclear matter symmetry energy at subsaturation densities. The slope parameter of the symmetry energy at the saturation density ${\ensuremath{\rho}}_{0}$ is $L=50.0\ifmmode\pm\else\textpm\fi{}15.5$ MeV. Furthermore, it is found that at the density of $\ensuremath{\rho}=0.69{\ensuremath{\rho}}_{0}=0.11$ fm${}^{\ensuremath{-}3}$, the symmetry energy $S(\ensuremath{\rho}=0.11\phantom{\rule{0.28em}{0ex}}{\mathrm{fm}}^{\ensuremath{-}3})=25.98\ifmmode\pm\else\textpm\fi{}0.01$ MeV and the corresponding slope parameter is $L=49.6\ifmmode\pm\else\textpm\fi{}6.2$ MeV, which are consistent with other independent analyses.