Measurement of the (anti-)3He elliptic flow in Pb-Pb collisions at √{sNN } = 5.02TeV

The elliptic flow (v₂) of (anti-)³He is measured in Pb-Pb collisions at √{s_NN } = 5.02TeV in the transverse-momentum (p_T) range of 2-6 GeV/c for the centrality classes 0-20%, 20-40%, and 40-60% using the event-plane method. This measurement is compared to that of pions, kaons, and protons at the same center-of-mass energy. A clear mass ordering is observed at low p_T, as expected from relativistic hydrodynamics. The violation of the scaling of v₂ with the number of constituent quarks at low p_T, already observed for identified hadrons and deuterons at LHC energies, is confirmed also for (anti-)³He. The elliptic flow of (anti-)³He is underestimated by the Blast-Wave model and overestimated by a simple coalescence approach based on nucleon scaling. The elliptic flow of (anti-)³He measured in the centrality classes 0-20% and 20-40% is well described by a more sophisticated coalescence model where the phase-space distributions of protons and neutrons are generated using the iEBE-VISHNU hybrid model with AMPT initial conditions.