Pion Production in Heavy-ion Collisions in the 1 A GeV region

Within the framework of the improved isospin dependent quantum molecular dynamics (ImIQMD) model, the pion emission in heavy-ion collisions in the region 1 A GeV is investigated systematically, in which the pion is considered to be mainly produced by the decay of resonances $\triangle$(1232) and N*(1440). The in-medium dependence and Coulomb effects of the pion production are included in the calculation. Total pion multiplicity and $\pi^{-}/\pi^{+}$ yields are calculated for the reaction $^{197}$Au+$^{197}$Au in central collisions for selected Skyrme parameters SkP, SLy6, Ska, SIII and compared them with the measured data by the FOPI collaboration.