The Study Of Nuclear Symmetry Energy

In this paper, we discussed the development history and significance of the relativistic meanfield, and on this basis expounded the research significance of nuclear symmetry energy. Twodifferent models of relativistic mean field theory have been used in studying the nuclearsymmetry energy and its derivatives. Base on above, this paper mainly carried out tworesearches.In the first part, on the base of mean field approximation of nonlinear relativistic mean fieldmodel, we can study the nuclear symmetry energy and its derivatives. The results showed that asthe baryon density increased, the symmetry energy grew linearly even for different couplingconstant. And it has nothing to do with the incompressible coefficient K0of infinite symmetricnuclear matter at saturated density. The coupling constantsg andg have greater effect onthe nuclear symmetry energy than the self-coupling constants c and d. In particular, slope Land curvatureK symof nuclear symmetry energy at saturation density were decided respectivelybyg andg.In the second part, assuming coupling constants being density-dependent, we studied thenuclear symmetry energy and its derivatives. Meantime, we analyzed the difference between themodel and nonlinear model. In this paper, we used two different numerical methods to calculatenuclear symmetry energy, and both got a softer density dependence. The value of nuclearsymmetry energy by difference method is about1MeV less than that by derivation methodwhich has little influence around saturation density, but big influence in the high density.