Collision energy dependence of elliptic flow splitting between particles and their antiparticles from an extended multiphase transport model

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 study 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.

Figure 1

Reduced nonrelativistic mean-field potentials for (a) up quarks and anti-up quarks, (b) strange quarks and antistrange quarks, (c) nucleons and antinucleons, (d) and $K^{+}$ and $K^{-}$ in the cold antiquark- or antibaryon-free nuclear medium.

Figure 2

Differential elliptic flow of mid-pseudorapidity ($\left|\eta \right|<1$) particles in mid-central (20%–30%) $\text{Au}+\text{Au}$ collisions at (a) $\sqrt{s_{NN}^{}}=7.7$, (b) 11.5, (c) 19.6, (d) 27, and (e) 39 GeV with different values of $R_V$. The experimental data are taken from Ref. [39].

Figure 3

Time evolution of densities of quarks and antiquarks (left columns) as well as baryons and antibaryons (right columns) in central cells of the partonic and the hadronic phase, respectively, in mid-central (20%–30%) $\text{Au}+\text{Au}$ collisions at $\sqrt{s_{NN}^{}}=7.7$, $11.5,19.6,27$, and 39 GeV.

Figure 4

The elliptic flow difference between midrapidity light quarks and their antiquarks (upper panels) as well as that between midrapidity strange quarks and antistrange quarks (lower panels) at the end of the partonic phase in mini-bias (0%–80%) $\text{Au}+\text{Au}$ collisions at $\sqrt{s_{NN}^{}}=7.7$, $11.5,19.6,27$, and 39 GeV, with $R_V=0,0.5$, and 1.1.

Figure 5

The relative elliptic flow difference between midrapidity nucleons and antinucleons (upper panels) and that between midrapidity $K^{+}$ and $K^{-}$ (lower panels) in the final stage of mini-bias (0%–80%) $\text{Au}+\text{Au}$ collisions at $\sqrt{s_{NN}^{}}=7.7,11.5$, and 39 GeV, with $R_V=0,0.5$, and 1.1, and experimental data from Ref. [43].

Figure 6

The elliptic flow difference between midrapidity nucleons and antinucleons (upper panels) as well as that between midrapidity $K^{+}$ and $K^{-}$ (lower panels) in the final stage of mini-bias (0%–80%) $\text{Au}+\text{Au}$ collisions at $\sqrt{s_{NN}^{}}=7.7,11.5$, $19.6,27$, and 39 GeV, with $R_V=0,0.5$, and 1.1, and experimental data from Ref. [44].