Abstract
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 root s(NN) = 200 GeV. The charged hadron is measured at midrapidity vertical bar eta vertical bar < 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 vertical bar Delta eta vertical bar > 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(+/-) 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 root 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.
