Transverse momentum decorrelation of the flow vector in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV

Abstract: The individual studies of the anisotropic flow vector, flow angle and flow magnitude fluctuations with multi-particle correlations provide insight into the initial conditions and properties of the quark-gluon plasma (QGP) created in high-energy heavy-ion collisions. Recent measurements of these fluctuations have been available and the comparison to hydrodynamic models shows unique sensitivities to the initial conditions of the system, but also a puzzling dependence on the specific shear viscosity $\eta/s$. In this paper, a systematic study with A Multi-Phase Transport (AMPT) model using different tunings of the initial conditions, partonic cross section and hadronic interactions investigates the $p_{\rm T}$-dependent flow vector, flow angle and flow magnitude fluctuations. It is found that the transport model reasonably describes the flow vector, flow angle and flow magnitude fluctuations observed in data and that the fluctuations are driven by fluctuations in the initial state. The comparison of data and model presented in this paper enables further constraints on the initial conditions of the heavy-ion collisions.