Study of J/ψ azimuthal anisotropy at forward rapidity in Pb-Pb collisions at √sNN=5.02 TeV
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The second (v2) and third (v3) flow harmonic coefficients of J/ψ mesons are measured at forward rapidity (2.5 < y < 4.0) in Pb-Pb collisions at √ sNN = 5.02 TeV with the ALICE detector at the LHC. Results are obtained with the scalar product method and reported as a function of transverse momentum, pT, for various collision centralities. A positive value of J/ψ v3 is observed with 3.7σ significance. The measurements, compared to those of prompt D0 mesons and charged particles at mid-rapidity, indicate an ordering with vn(J/ψ) < vn(D0 ) < vn(h±) (n = 2, 3) at low and intermediate pT up to 6 GeV/c and a convergence with v2(J/ψ) ≈ v2(D0 ) ≈ v2(h±) at high pT above 6–8 GeV/c. In semicentral collisions (5–40% and 10–50% centrality intervals) at intermediate pT between 2 and 6 GeV/c, the ratio v3/v2 of J/ψ mesons is found to be significantly lower (4.6σ) with respect to that of charged particles. In addition, the comparison to the prompt D0 -meson ratio in the same pT interval suggests an ordering similar to that of the v2 and v3 coefficients. The J/ψ v2 coefficient is further studied using the Event Shape Engineering technique. The obtained results are found to be compatible with the expected variations of the eccentricity of the initial-state geometry.
CitationAcharya S, Acosta FT, Adamová D, Adler C, Adolfsson J, Aggarwal MM, Aglieri Rinella G, Agnello M, Agrawal N, Ahammed Z, Alme J, Altenkaemper L, Djuvsland Ø, Fionda FMC, Nystrand J, Røhrich D, Tambave GJ, Ullaland K, Wagner B, Zhou Z, Arsene IC, Bätzing P, Dordic O, Ersdal MR, Lardeux A, Lindal S, Malik QW, Mahmood SM, Rehman Au, Richter M, Røed K, Skaali TB, Tveter TS, Wikne JC, Zhao C, Helstrup H, Hetland KF, Kileng B, Nesbø SV, Storetvedt M, Langøy R, Lien JA, Ahn SU, Aiola S, Akindinov A, Al-Turany M, Alam SN, De Albuquerque DS, Aleksandrov D, Alessandro B, ALICE C. Study of J/ψ azimuthal anisotropy at forward rapidity in Pb-Pb collisions at √sNN=5.02 TeV. Journal of High Energy Physics (JHEP). 2019;12.
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