Long-range angular correlations of π, K and p in p–Pb collisions at sqrt(s_NN) = 5.02 TeV

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5.02 TeV
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Angular correlations between unidentified charged trigger particles and different species of charged associated particles (unidentified particles, pions, kaons, protons and antiprotons) are measured by the ALICE detector in p–Pb collisions at a nucleon–nucleon centre-of- mass energy of 5.02 TeV in the transverse-momentum range 0.p4 GeV/c. The correlations are measured in the pseudorapidity range |ηlab0.8 and full azimuthal angle and are expressed as associated yield per trigger particle. Fourier coefficients are extracted from the long-range correlations projected onto the azimuthal angle difference and studied as a function of pand in intervals of event multiplicity. In high-multiplicity events, the second-order coefficient vpis observed to be smaller than vπup to about p2 GeV/c. Further, to reduce jet correlations, the per-trigger yield obtained in low-multiplicity events is subtracted from the one in high-multiplicity events. A two-ridge structure is obtained for all particle species. The quantification of this structure with Fourier coefficients shows that vπand vKare similar, while vpis found to be smaller at low pand larger at higher pthan vπand vK. The crossing occurs at about 2 GeV/c. This is qualitatively similar to the elliptic flow pattern observed in heavy-ion collisions and consistent with expectations from hydrodynamic calculations.