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

We extract the mass-dependent symmetry energy coefficients $a_{\text{sym}}(A)$ with the nuclear mass differences reducing the uncertainties as far as possible. The estimated $a_{\text{sym}}(A)$ of ${}^{208}\text{Pb}$ is $22.4\pm 0.3$ 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 ${\rho }_0$ is $L=50.0\pm 15.5$ MeV. Furthermore, it is found that, at the density of $\rho =0.69{\rho }_0=0.11$fm${}^{-3}$, the symmetry energy $S(\rho =0.11{\text{fm}}^{-3})=25.98\pm 0.01$ MeV and the correspondingly slope parameter is $L=49.6\pm 6.2$ MeV, which are consistent with other independent analysis.