Analysis of the dynamical mechanism for elliptic flow production in heavy-ion collisions at intermediate energies

Elliptic flow (nu(2)) is an essential observable for studying the dynamic process of heavy-ion collisions, and has attracted significant attention in recent years. Based on the ultra-relativistic quantum molecular dynamics model, by tracking the nucleons that are emitted at mid-rapidity (vertical bar y(0)vertical bar < 0.1) in the entire collision process, the time evolution of elliptic flow of these selected nucleons is studied. The contributions of the mean-field potential and collision term to the elliptic flow are disentangled by recording the momenta of nucleons before and after each collision and propagation in the potential. In the semi-peripheral (b =5 fm) Au +Au collision at E-beam = 0.4 GeV/nucleon, approximately 30% of the nu(2) is attributed to the mean-field potential, while the remaining 70% is attributed to the nucleon-nucleon collisions. nu(2) is further increased (by approximately 10%) if the Pauli blocking effect is excluded.