  Based on an extended multiphase transport model, which includes mean-field
potentials in both the partonic and hadronic phases, uses the mix-event
coalescence, and respects charge conservation during the hadronic evolution, we
have studied the collision energy dependence of the elliptic flow splitting
between particles and their antiparticles. This extended transport model
reproduces reasonably well the experimental data at lower collision energies
but only describes qualitatively the elliptic flow splitting at higher beam
energies. The present study thus indicates the existence of other mechanisms
for the elliptic flow splitting besides the mean-field potentials and the need
of further improvements of the multiphase transport model.
