Correlation between symmetry energy and effectivek-mass splitting with an improved isospin- and momentum-dependent interaction

Abstract

The isospin- and momentum-dependent interaction using the isospin-dependent quantum molecular dynamics model is improved. The momentum dependence of the interaction is fitted to the optical potentials extracted with proton-nucleus scattering data, while the isospin dependence is adjusted based on the current constraints on the symmetry energy and its density slope at normal density. The resulting parameters of the interaction are used to calculate the effective masses characterized by the nonlocality of the nuclear potential in the spatial coordinates (the so-called effective $k$ masses). It is found that this parametrization can reproduce the effective $k$ masses calculated by the Dirac-Brueckner-Hartree-Fock model. The current constraints on the total symmetry energy can accommodate a wide-range adjustment of the local symmetry energy and effective $k$-mass splitting. Four groups of parameters, which provide different density dependences of symmetry energy and effective $k$-mass splitting, are applied to investigate the isospin diffusion and neutron to proton double ratios in collisions involving $^{124}\mathrm{Sn}$ and $^{112}\mathrm{Sn}$ nuclei at 50 and 120 MeV/nucleon. Calculations confirm the sensitivity of symmetry energy to the isospin diffusion, but indicate the synchronous effects of symmetry energy and effective $k$-mass splitting on the double ratios.