Higher harmonic anisotropic flow of identified particles in Pb-Pb collisions with the ALICE detector

Abstract

Anisotropic flow plays a crucial role in establishing the equation of state of the Quark Gluon Plasma. The results at RHIC and LHC have demonstrated that the matter created in heavy-ion collisions behaves as a nearly perfect fluid reflected in the low value of the shear viscosity over entropy density ratio ($η/s$). The higher flow harmonics are particularly sensitive to the value of $η/s$ in hydrodynamic calculations. In this analysis, we present the first ALICE results on the $p_{\mathrm{T}}$ differential $v_{2}$, $v_{3}$ and $v_{4}$ for $π^{\pm}$, $\mathrm{K}^{\pm}$, p($\bar p$) from the high statistics 2011 heavy-ion run. We investigate how these $v_{n}$ coefficients evolve with particle mass and centrality for the 0--1\% and 20--30\% centrality ranges. These new measurements aim at differentiating between models that use different initial conditions, constraining further the value of $η/s$ and allowing to decouple the influence of the late hadronic stage from the hydrodynamic evolution of the system.