Production of Subthreshold Pions in Heavy-Ion Collisions Using a Hydrodynamic Approach with a Nonequilibrium Equation of State

Abstract

A hydrodynamic approach with a nonequilibrium equation of state is used to describe collisions between heavy ions with medium energies. The double differential cross sections for the production of subthreshold $${{\pi }^{0}}$$ mesons and $${{\pi }^{ + }}$$ mesons during collisions between various nuclei are calculated to develop this approach with the inclusion of nuclear viscosity effects. They are in good agreement with the available experimental data.