Microscopic calculation of pion production in nucleus-nucleus collisions around 1 GeV�A

Abstract

The pion production cross section in nucleus-nucleus collisions at aboutElab/A=1 GeV is calculated within the relativistic (RQMD) and the nonrelativistic quantum molecular dynamics (QMD) approach. We use both soft and hard equations of state (EOS) with and without the momentum dependence in the interaction. For the nucleon-nucleon (NN) cross section, isospin-dependent Cugnon parameterization and BruecknerG-matrix ones are utilized. A parameterized cross section is used for pion production in baryon-baryon collisions. The reabsorption of pions in the nuclear medium is taken into account in an empirical way. A detailed comparison is made between the pion production cross sections obtained in RQMD and QMD, with soft and hard EOS, with and without the momentum dependence in the in-medium NN interaction, with different NN cross sections and with different pion mean free paths. The agreement between the theoretical results and available experimental data is encouraging, although no definite and systematical evidence is found concerning the incompressibility of nuclear matter and the significance of a fully Lorentz covariant treatment of heavy-ion collisions at present energy domain.