Search for collectivity with azimuthal J/\(psi\)-hadron correlations in high multiplicity p-Pb collisions at \(\sqrt{s_{\rm NN}}\) = 5.02 and 8.16 TeV

Abstract

We present a measurement of azimuthal correlations between inclusive J/\).psi\) and charged hadrons in p-Pb collisions recorded with the ALICE detector at the CERN LHC. The J/\).psi\) are reconstructed at forward (p-going, 2.03 \(<\) y \(<\) 3.53) and backward (Pb-going, \(-\)..46 \(<\) y \(<\) \(-\)..96) rapidity via their \(\mu^+\mu^-\) decay channel, while the charged hadrons are reconstructed at mid-rapidity \(|\eta|\) \(<\) 1.8). The correlations are expressed in terms of associated charged-hadron yields per J/\).psi\) trigger. A rapidity gap of at least 1.5 units is required between the trigger J/\).psi\) 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 \(\Delta\varphi\) \(\approx\) 0 and \(\Delta\varphi\) \(\approx\) \(\pi\). similar to those previously found in two-particle correlations at middle and forward rapidity. The corresponding second-order Fourier coefficient \(v_2\) in the transverse momentum interval between 3 and 6 GeV/\).\) is found to be positive with a significance of about 5\).sigma\). The obtained results are similar to the J/\).psi\) \(v_2\) coefficients measured in Pb-Pb collisions at \(\sqrt{s_{\rm NN}}\) = 5.02 TeV, suggesting a common mechanism at the origin of the J/\).psi\) \(v_2\).