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

We extract the mass-dependent symmetry energy coefficients a(sym)(A) with the nuclear mass differences reducing the uncertainties as far as possible. The estimated asym(A) of Pb-208 is 22.4 +/- 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 +/- 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 fm(-3)) = 25.98 +/- 0.01 MeV and the corresponding slope parameter is L = 49.6 +/- 6.2 MeV, which are consistent with other independent analyses.