Influence of Fermi momentum on elliptic flow in heavy-ion collisions at intermediate energies

BackgroundElliptic flow (v2) is one of the most important observations for exploring the properties of nuclear matter using heavy-ion collisions. v2 is not only affected by dynamic processes but is also related to the Fermi momentum of the initial nucleus.PurposeThis study aims to quantitatively determine the effect of the initial Fermi momentum on the time evolution of v2.MethodsFirst, based on the Ultrarelativistic Quantum Molecular Dynamics (UrQMD) model, gold-gold (Au+Au) collisions at beam energies of 0.4A GeV and 0.8A GeV with impact parameter b = 6 fm were simulated. In the initial stage, three cases were considered: without Fermi momentum, with Fermi momentum, and with half-Fermi momentum. Then, by reverse tracing the nucleons that were emitted at mid-rapidity (|y0|