Pseudorapidity dependence of long-range two-particle correlations in pPb collisions at root sNN=5.02 TeV

Two-particle correlations in p Pb collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV are studied as a function of the pseudorapidity separation ( Δ η ) of the particle pair at small relative azimuthal angle ( | Δ ϕ | < π / 3 ). The correlations are decomposed into a jet component that dominates the short-range correlations ( | Δ η | < 1 ), and a component that persists at large Δ η and may originate from collective behavior of the produced system. The events are classified in terms of the multiplicity of the produced particles. Finite azimuthal anisotropies are observed in high-multiplicity events. The second and third Fourier components of the particle-pair azimuthal correlations, V 2 and V 3 , are extracted after subtraction of the jet component. The single-particle anisotropy parameters v 2 and v 3 are normalized by their laboratory frame midrapidity value and are studied as a function of η c.m. . The normalized v 2 distribution is found to be asymmetric about η c.m. = 0 , with smaller values observed at forward pseudorapidity, corresponding to the direction of the proton beam, while no significant pseudorapidity dependence is observed for the normalized v 3 distribution within the statistical uncertainties