engleski

Search for collectivity with azimuthal J/ψ-hadron correlations in high multiplicity p-Pb collisions at √sNN = 5.02 and 8.16 TeV

We present a measurement of azimuthal correlations between inclusive J/ψ and charged hadrons in p–Pb collisions recorded with the ALICE detector at the CERN LHC. The J/ ψ are reconstructed at forward (p-going, 2.03<y<3.53) and backward (Pb-going, −4.46<y<−2.96) rapidity via their μ+μ− decay channel, while the charged hadrons are reconstructed at mid-rapidity ( |η|<1.8 ). The correlations are expressed in terms of associated charged- hadron yields per J/ ψ trigger. A rapidity gap of at least 1.5 units is required between the trigger J/ψ and the associated charged hadrons. Possible correlations due to collective effects are assessed by subtracting the associated per- trigger yields in the low-multiplicity collisions from those in the high-multiplicity collisions. After the subtraction, we observe a strong indication of remaining symmetric structures at Δφ≈0 and Δφ≈π , similar to those previously found in two-particle correlations at middle and forward rapidity. The corresponding second-order Fourier coefficient (v2) in the transverse momentum interval between 3 and 6 GeV/c is found to be positive with a significance of about 5 σ . The obtained results are similar to the J/ψ v2 coefficients measured in Pb–Pb collisions at sNN=5.02 TeV, suggesting a common mechanism at the origin of the J/ψ v2 .

correlation: two-particle ; rapidity: gap ; multiplicity: high ; heavy ion: scattering ; hadron ; trigger ; angular correlation ; transverse momentum ; CERN LHC Coll ; collective ; structure ; CERN Lab ; ALICE

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