"Figure 4a" of "Measurement of long-range angular correlation and quadrupole anisotropy of pions and (anti)protons in central $d+$Au collisions at $\sqrt{s_{_{NN}}}$=200 GeV"

We present azimuthal angular correlations between charged hadrons and energy deposited in calorimeter towers in central $d$+Au and minimum bias $p$+$p$ collisions at $\sqrt{s_{NN}}$ = 200 GeV. The charged hadron is measured at midrapidity $|\eta|$ < 0.35, and the energy is measured at large rapidity (−3.7 < $\eta$ < −3.1, Au-going direction). An enhanced near-side angular correlation across $|\Delta\eta|$ > 2.75 is observed in $d$+Au collisions. Using the event plane method applied to the Au-going energy distribution, we extract the anisotropy strength $v_2$ for inclusive charged hadrons at midrapidity up to $p_T$ = 4.5 GeV/$c$. We also present the measurement of $v_2$ for identified $\pi^{\pm}$ and (anti)protons in central $d$+Au collisions, and observe a mass-ordering pattern similar to that seen in heavy ion collisions. These results are compared with viscous hydrodynamic calculations and measurements from $p$+Pb at $\sqrt{s_{NN}}$ = 5.02 TeV. The magnitude of the mass-ordering in $d$+Au is found to be smaller than that in $p$+Pb collisions, which may indicate smaller radial flow in lower energy $d$+Au collisions.

Measured $v_2$ ($p_T$) for identified pions, each charged combined, 0-5% central $d$+Au collisions at RHIC.