Nuclear medium effect on nuclear modification factor of protons and pions in intermediate-energy heavy ion collisions
Ming Lv🇨🇳 · Yu-Gang Ma🇨🇳 · Jin-Hui Chen🇨🇳 · De-Qing Fang🇨🇳 · Guo-Qiang Zhang🇨🇳
Nuclear modification factor () of protons and pions are investigated by simulating Au + Au collisions from 0.8 to 1.8 GeV in a framework of an isospin-dependent quantum molecular dynamics (IQMD) model. of protons rises with the increase of \pt~ at different beam energies owing to radial flow and Cronin effect. The rate of increase of \rcp~ is suppressed at higher beam energies. The significant difference of between protons and pions indicates different medium effects between protons and pions. By changing the in-medium nucleon-nucleon cross section, the of protons changes a lot, while the of pions does not. Taking the pion absorption into account, the of pions becomes close to unity without dependence after deactivating the reaction , while there is nearly no change on proton. This suggests that the pion absorption plays a dominant role on pion dynamics and have slight effect for proton dynamics.