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

Abstract

We present a measurement of azimuthal correlations between inclusive J/? and charged hadrons in p�Pb collisions recorded with the ALICE detector at the CERN LHC. The J/? are reconstructed at forward (p-going, 2.03<y<3.53) and backward (Pb-going, ?4.46<y<?2.96) rapidity via their ?+?? decay channel, while the charged hadrons are reconstructed at mid-rapidity (|?|<1.8). The correlations are expressed in terms of associated charged-hadron yields per J/? trigger. A rapidity gap of at least 1.5 units is required between the trigger J/? 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 ???0 and ???? 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?. The obtained results are similar to the J/? v2 coefficients measured in Pb�Pb collisions at sNN=5.02 TeV, suggesting a common mechanism at the origin of the J/? v2. � 2018 The Author