Measurement of the (anti-)$^3$He elliptic flow in Pb-Pb collisions at $\sqrt{s_{NN}} = 5.02$ TeV

S. Acharya , Daniel Dąbrowski , Kamil Deja , Łukasz Graczykowski , Monika Jakubowska , Małgorzata Janik , Adam Kisiel , Julian Myrcha , Piotr Nowakowski , Janusz Oleniacz , Jan Pluta , Przemysław Rokita , Krystian Rosłon , Tomasz Trzciński , Hanna Zbroszczyk

Abstract

The elliptic flow (v2) of (anti-)$^3$. He is measured in Pb-Pb collisions at $\sqrt{s_{NN}} = 5.02$ TeV in the transverse-momentum (pT) 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 pT, as expected from relativistic hydrodynamics. The violation of the scaling of $v_2$ with the number of constituent quarks at low \pt, already observed for identified hadrons and deuterons at LHC energies, is confirmed also for (anti-)3He. The elliptic flow of (anti-)$^3$. He is underestimated by the Blast-Wave model and overestimated by a simple coalescence approach based on nucleon scaling. The elliptic flow of (anti-)$^3$. He 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.