Probing the density dependence of the symmetry energy with central heavy ion collisions 后印本

摘要: An improved isospin dependent Boltzmann Langevin model, in which the inelastic channels and momentum dependent interactions are incorporated, is used to investigate the high-density behavior of nuclear symmetry energy. By taking several forms of nuclear symmetry energy, we calculate the time evolutions of neutron over proton ratio, π multiplicity and π−/π+ ratio, and the kinetic energy and transverse momentum spectra of π−/π+ ratio in the heavy ion collisions at 400A MeV. It is found that the neutron over proton ratio and π−/π+ ratio are very sensitive to the nuclear symmetry energy, and the π^– is more sensitive to the nuclear symmetry energy than the π⁺. A supersoft symmetry energy results in a larger π−/π+ ratio.