CERN Accelerating science

The elusive goal of heavy-ion physics is to understand the transport properties of the quark-gluon plasma (QGP), the form of nuclear matter at extreme temperatures, that prevailed in the first few microseconds after the Big Bang. Transport coefficients, such as the temperature dependent specific shear viscosity $\eta/s$ and specific bulk viscosity $\zeta/s$, can be constrained with the help of flow measurements. The higher harmonic flow observables and their non-linear responses to the initial state anisotropy have shown compelling potential to constrain the transport properties due to their high sensitivity to various stages of heavy-ion collisions. In this thesis, the measurements of higher harmonic flow up to the ninth order, and their non-linear flow modes up to the seventh harmonic in Pb--Pb collisions with ALICE at CERN-LHC are presented. These measurements are utilized in a Bayesian analysis to constrain the QGP properties and initial conditions of such collisions. In addition, the sensitivities of the high harmonic flow observables to various model parameters are quantified for the first time. This work suggests that a more dynamical picture of the initial conditions is needed to improve the understanding of the uncertainties of the extracted QGP properties or the model building blocks.