Measurement of emission-angle anisotropy via long-range angular correlations with high-pT hadrons in d+Au and p+p collisions at √sNN = 200 GeV

Abstract

We present measurements of two-particle angular correlations between high-transverse-momentum (2 < pT < 11 GeV/c) π0 observed at midrapidity (|η| < 0.35) and particles produced either at forward (3.1 <η< 3.9) or backward (−3.7 <η< −3.1) rapidity in d + Au and p + p collisions at √sNN = 200 GeV. The azimuthal angle correlations for particle pairs with this large rapidity gap in the Au-going direction exhibit a characteristic structure that persists up to pT ≈ 6 GeV/c and which strongly depends on collision centrality, which is a similar characteristic to the hydrodynamical particle flow in A + A collisions. The structure is absent in the d-going direction as well as in p + p collisions, in the transverse-momentum range studied. The results indicate that the structure is shifted in the Au-going direction toward more central collisions, similar to the charged-particle pseudorapidity distributions.