Elliptic Flow Splitting between Particles and their Antiparticles in Au+Au Collisions from a Multiphase Transport Model

The elliptic flow v_2, for \pi^\pm, K^\pm, p and \bar p in Au+Au collisions at center-of-mass energies \sqrt s__\rm NN=7.7, 11.5, 14.5 and 19.6 GeV, is analyzed using a multiphase transport model. A significant difference in the v_2 values for p and \bar p is observed, and the values of v_2 splitting are larger compared with \pi^+ and \pi^-, K^+ and K^-. The difference increases with decreasing the center-of-mass energy. The effect of the quark coalescence mechanism in a multi-phase transport model to the value of elliptic difference \Delta v_2 between p and \bar p has been discussed. The simulation of Au+Au collisions at 14.5 GeV shows that the effect of hadron cascade to \Delta v_2 is not obvious, and a larger parton-scattering cross section can lead to a larger \Delta v_2.