Anisotropic flow in $\text{Cu}+\text{Au}$ collisions at $\sqrt{s_{\mathit{NN}}}=200$ GeV

The anisotropic flow of charged hadrons in asymmetric $\text{Cu}+\text{Au}$ collisions at the Relativistic Heavy Ion Collider is studied in a multiphase transport model. Compared with previous results for symmetric $\text{Au}+\text{Au}$ collisions, charged hadrons produced around midrapidity in asymmetric collisions are found to have a stronger directed flow $v_1$ and their elliptic flow $v_2$ is also more sensitive to the parton scattering cross section. Although higher order flows $v_3$ and $v_4$ are small at all rapidities, both $v_1$ and $v_2$ in these collisions are appreciable and show an asymmetry in forward and backward rapidities.

Figure 1

(Color online) Pseudorapidity dependence of $v_1$(a) and $v_3$(b) for charged hadrons from minimum bias events of $\text{Cu}+\text{Au}$ collisions at $\sqrt{s}=200A$ GeV by using the string melting scenario with parton scattering cross sections ${\sigma }_p=3$ (open squares) and 10 mb (solid squares) and the default AMPT model without string melting (solid triangles).

Figure 2

(Color online) Same as Fig. 1 for $v_2$ and $v_4$.

Figure 3

(Color online) $p_T$ dependence of $v_1$ [(a) and (b)], $v_2$ [(c) and (d)], $v_3$ [(e) and (f )], and $v_4$ [(g) and (h)] for charged hadrons at forward mid-$\eta$ ($0<\eta <1.2$, left panels) and backward mid-$\eta$ ($-1.2<\eta <0$, right panels) from minimum bias events of $\text{Cu}+\text{Au}$ collisions at $\sqrt{s}=200A$ GeV.

Figure 4

(Color online) Time evolutions of $s_1$ (a), $s_2$ (b), $v_1$ (c), and $v_2$ (d) of partons at forward mid-$\eta$ ($0<\eta <1.2$, solid squares) and backward mid-$\eta$ ($-1.2<\eta <0$, open squares) from $\text{Cu}+\text{Au}$ collisions at $\sqrt{s}=200A$ GeV and $b=6.74$ fm in the scenario of string melting with ${\sigma }_p=10$ mb.

Figure 5

(Color online) Same as Fig. 4 but for $s_3$ (a), $s_4$ (b), $v_3$ (c), and $v_4$ (d).

Figure 6

(Color online) $p_T$ dependence of $v_1$ (a), $v_2$ (b), $v_3$ (c), and $v_4$ (d) for charged hadrons at large forward pseudorapidity ($\eta =4$, solid squares) and backward pseudorapidity ($\eta =-4$, open squares) from minimum bias events of $\text{Cu}+\text{Au}$ collisions at $\sqrt{s}=200A$ GeV.

Figure 7

(Color online) Charged hadron pseudorapidity density for minimum bias events of $\text{Cu}+\text{Au}$ collisions at $\sqrt{s}=200A$ GeV from the AMPT model in the scenario without string melting.