The role of three-body forces in nuclear symmetry energy and symmetry free energy

Within the framework of lowest-order constrained variational (LOCV) method using AV18 two-body interaction supplemented by UIX three-body force, equation of state of asymmetric nuclear matter at both zero and finite temperature is studied. Density dependence of the nuclear symmetry energy as well as its partial wave decomposition is also investigated. It is shown that all saturation properties of the cold symmetric nuclear matter, including the symmetry energy and its slope, can be correctly reproduced if the three-body force is used in the LOCV formalism. Furthermore, density and temperature dependence of the symmetry energy and symmetry free energy in hot neutron rich matter is studied. An opposite temperature dependence for the symmetry energy and symmetry free energy is found.