Anisotropic flow of identified particles in Pb–Pb collisions at √s_NN = 2.76 TeV measured with ALICE at the LHC

¹ Museo storico della fisica e centro studi e ricerche “E. Fermi”
² INFN, Bologna ( Italy )

^a e-mail: Francesco.Noferini@cern.ch, Francesco.Noferini@bo.infn.it

Published online: 24 March 2015

Abstract

The anisotropic flow (υ_n) of identified particles is an important observable to probe the freeze-out properties, the parton energy loss and the transport coefficients of the system created in heavy-ion collisions. We report on the anisotropic flow measurements for a number of identified particles such as charged pions, kaons and (anti-)protons, as well as K⁰_s, Λ(Λ̄), ϕ, Ξ⁻(Ξ̅⁺), and Ω⁻(Ω̅⁺). The measurements are performed in the rapidity range |y| < 0.5, over a wide range of transverse momenta, 0.2 < p_T < 6 GeV/c, for Pb–Pb collisions at √s_NN = 2.76 TeV recorded by ALICE at the LHC. We will present the mass ordering as a function of transverse momentum for several collision centralities compared with results allower energies. While in the low p_T region hydrodynamical computations describe the experimental data points fairly well, at intermediate momenta the quark number (n_q) scaling indicates that it holds at an approximate level of 20–30%. Finally, focusing on the low momentum region ALICE has recently observed a similar mass ordering behaviour of υ₂ in p–Pb systems. We will present this intriguing result which may be connected to a collective effect similar to that observed in Pb–Pb collisions.