J/Psi Elliptic Flow in Pb-Pb Collisions at $\sqrt{s_{\rm NN}}$ = 2.76 TeV

TL;DR

This paper presents the first measurement of J/ψ elliptic flow in Pb-Pb collisions at 2.76 TeV, indicating non-zero flow and supporting the idea of charm quark participation in a deconfined quark-gluon plasma.

Contribution

It provides the first measurement of inclusive J/ψ elliptic flow at the LHC, revealing non-zero v2 and supporting charm quark participation in the quark-gluon plasma.

Findings

Indication of non-zero J/ψ v2 in semi-central collisions.

Maximum v2 value of 0.116 ± 0.046 (stat.) ± 0.029 (syst.) in 2-4 GeV/c pT range.

Supports charm quark participation in deconfined medium.

Abstract

We report on the first measurement of inclusive J/$\psi$ elliptic flow, $v_2$, in heavy-ion collisions at the LHC. The measurement is performed with the ALICE detector in Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV in the rapidity range $2.5 < y < 4.0$. The dependence of the J/$\psi$ $v_2$ on the collision centrality and on the J/$\psi$ transverse momentum is studied in the range $0 < p_{\rm T} < 10$ GeV/$c$. For semi-central Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV, an indication of non-zero $v_2$ is observed with a maximum value of $v_2 = 0.116 \pm 0.046 {\rm (stat.)} \pm 0.029 {\rm (syst.)}$ for J/$\psi$ in the transverse momentum range $2 < p_{\rm T} < 4$ GeV/$c$. The elliptic flow measurement complements the previously reported ALICE results on the inclusive J/$\psi$ nuclear modification factor and favors the scenario of a significant fraction of J/$\psi$ production from charm quarks in a deconfined partonic phase.