Roles of NΔ → NN and πN → Δ Reactions in Heavy-Ion Collisions at Intermediate Energies

Within the framework of the isospin-dependent transport model, the roles of the reactions N Delta -> NN and pi N -> Delta are investigated through simulating heavy-ion collisions at 1000 MeV/nucleon. The absorption process N Delta -> NN plays an important role for heavy impact systems and small impact parameters than for light impact systems and large impact parameters. The resorption process pi N -> Delta is of importance for heavy impact systems and large impact parameters than for light impact systems and small impact parameters. Thus the influences of the reaction N Delta -> NN (pi N -> Delta) on pion production dynamics can be neglected in heavy-ion collisions for smaller (larger) impact parameters and light systems. It is the reaction pi N -> Delta that causes the anti-correlation of pions and nucleons in the rapidity dependence of the directed flow.