The effect of inner magnetic field on collective flows from heavy-ion collisions at intermediate energies

Abstract

The properties of nuclear matter under extreme conditions (high temperature, density and isospin-asymmetry) have attracted a lot of attention in recent years. At present, heavy ion reactions in combination with corresponding model simulations are among the most important ways to investigate this subject. It is known that a strong inner magnetic field is created during the heavy ion collisions. Nevertheless, its effects on the motion of charged particles are usually not taken into account in previous transport model simulations for simplicity. Within the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) model, the effect of inner magnetic field on the emission of several charged particles is investigated. It is found that its effect on emitted nucleon related observables, such as yields and collective flows, is weak, while it is visible on pion related observables, such as π--π+ yield ratio and flows, as a function of rapidity. This result implies that it is necessary to consider the effect of inner magnetic field especially when the π mesons emitted from heavy ion collisions at intermediate energies are taken as a sensitive probe for the properties of nuclear matter.