Inclusive charged hadron elliptic flow in Au + Au collisions at $\sqrt{s_{NN}}$ = 7.7 - 39 GeV

The collaboration
Phys.Rev.C 86 (2012) 054908, 2012.

Abstract
A systematic study is presented for centrality, transverse momentum ($p_T$) and pseudorapidity ($\eta$) dependence of the inclusive charged hadron elliptic flow ($v_2$) at midrapidity($|\eta| < 1.0$) in Au+Au collisions at $\sqrt{s_{NN}}$ = 7.7, 11.5, 19.6, 27 and 39 GeV. The results obtained with different methods, including correlations with the event plane reconstructed in a region separated by a large pseudorapidity gap and 4-particle cumulants ($v_2{4}$), are presented in order to investigate non-flow correlations and $v_2$ fluctuations. We observe that the difference between $v_2{2}$ and $v_2{4}$ is smaller at the lower collision energies. Values of $v_2$, scaled by the initial coordinate space eccentricity, $v_{2}/\varepsilon$, as a function of $p_T$ are larger in more central collisions, suggesting stronger collective flow develops in more central collisions, similar to the results at higher collision energies. These results are compared to measurements at higher energies at the Relativistic Heavy Ion Collider ($\sqrt{s_{NN}}$ = 62.4 and 200 GeV) and at the Large Hadron Collider (Pb + Pb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV). The $v_2(p_T)$ values for fixed $p_T$ rise with increasing collision energy within the $p_T$ range studied ($< 2 {\rm GeV}/c$). A comparison to viscous hydrodynamic simulations is made to potentially help understand the energy dependence of $v_{2}(p_{T})$. We also compare the $v_2$ results to UrQMD and AMPT transport model calculations, and physics implications on the dominance of partonic versus hadronic phases in the system created at Beam Energy Scan (BES) energies are discussed.

• #### Table 2

Data from Figure 2

10.17182/hepdata.102951.v1/t1

The event plane resolutions for Au + Au collisions at $\sqrt{s_{NN}}$ = 7.7, 11.5, 19.6, 27 and 39 GeV as...

• #### Table 3

Data from Figure 3 (The official number for errors lower than 0.0001 is 0.0000)

10.17182/hepdata.102951.v1/t2

The comparison of $v_2$ as a function of $p_T$ between GF-cumulant and Q-cumulant methods in Au+Au collisions at $\sqrt{s_{NN}}$ =...

• #### Table 4

Data from Figure 4 (The official number for errors lower than 0.0001 is 0.0000)

10.17182/hepdata.102951.v1/t3

The $p_T$ (> 0.2 GeV/c) and $\eta$ ($∣\eta∣$ < 1) integrated $v_2$ as a function of collision centrality for Au...

• #### Table 5

Data from Figure 5 and Figure 11 (The official number for errors lower than 0.0001 is 0.0000)

10.17182/hepdata.102951.v1/t4

The $v_2$ as a function of $p_T$ for 20-30% central Au + Au collisions at midrapidity for $\sqrt{s_{NN}}$ = 7.7...

• #### Table 6

Glauber model from Figure 6 and Table 2

10.17182/hepdata.102951.v1/t5

$\varepsilon$ (Glauber) as a function of $p_T$ for various collision centralities (10-20%, 30-40% and 50-60%) in Au + Au collisions...

• #### Table 7

CGC model from Figure 7 and Table 3

10.17182/hepdata.102951.v1/t6

$\varepsilon$ (CGC) as a function of $p_T$ for various collision centralities (10-20%, 30-40% and 50-60%) in Au + Au collisions...

• #### Table 67

Data from Figures 6, 7 and 11 (The official number for errors lower than 0.0001 is 0.0000)

10.17182/hepdata.102951.v1/t7

$v_2${EtaSubs} as a function of $p_T$ for various collision centralities (10-20%, 30-40% and 50-60%) in Au + Au collisions at...

• #### Table 8

Data from Figure 8

10.17182/hepdata.102951.v1/t8

The $v_2${EP} vs. $\eta$ for 10-40% centrality in Au + Au collisions at $\sqrt{s_{NN}}$ = 7.7 GeV, 11.5 GeV, 19.6...

• #### Table 8a

Data from Figure 8

10.17182/hepdata.102951.v1/t9

The $v_2${EP} vs. $\eta$ for 10-40% centrality in Au + Au collisions at $\sqrt{s_{NN}}$ = 62.4 GeV.

• #### Table 9

Data from Figures 9, 10 and 12

10.17182/hepdata.102951.v1/t10

The $v_2${4} vs. $p_T$ at midrapidity for various collision energies ($\sqrt{s_{NN}}$ = 7.7 GeV, 11.5 GeV, 19.6 GeV, 27 GeV...

• #### Table 9b

Data from Figures 9 and 10

10.17182/hepdata.102951.v1/t11

The $v_2${4} vs. $p_T$ at midrapidity for $\sqrt{s_{NN}}$ = 62.4 GeV.

• #### Table 9c

Data from Figures 9, 10 and 12

10.17182/hepdata.102951.v1/t12

The $v_2${4} vs. $p_T$ at midrapidity for $\sqrt{s_{NN}}$ = 200 GeV.