With A Multi-Phase Transport (AMPT) model we investigate the relation between the magnitude, fluctuations and correlations of the initial state spatial anisotropy εn and the final state anisotropic flow coefficients vn in Au+Au collisions at √ s NN = 200 GeV. It is found that the relative eccentricity fluctuations in AMPT account for the observed elliptic flow fluctuations, both are in agreement with the elliptic flow fluctuation measurements from the STAR collaboration. In addition, the studies based on 2-and multi-particle correlations and event-by-event distributions of the anisotropies suggest that the Elliptic-Power function is a promising candidate of the underlying probability density function of the event-by-event distributions of εn as well as vn. Furthermore, the correlations between different order symmetry planes and harmonics in the initial coordinate space and final state momentum space are presented. Non-zero values of these correlations have been observed. The comparison between our calculations and data will, in the future, shed new insight into the nature of the fluctuations of the Quark-Gluon Plasma produced in heavy ion collisions.

Within a multiphase transport model, we investigate decorrelation of event planes over pseudorapidity and its effect on azimuthal anisotropy measurements in relativistic heavy-ion collisions. The decorrelation increases with increasing η gap between particles used to reconstruct the event planes. The third harmonic event planes are found even anticorrelated between forward and backward rapidities, the source of which may root in the opposite orientation of the collision geometry triangularities. The decorrelation may call into question the anisotropic flow measurements with pseudorapidity gap designed to reduce nonflow contributions, hence the hydrodynamic properties of the quark-gluon plasma extracted from those measurements.

It is crucially important to find an observable which is independent on the acceptance and late collision process, in order to search for the possible Critical Point predicted by QCD. By utilizing A Multi-Phase Transport (AMPT) model and Ultra Relativistic Quantum Molecular Dynamics (UrQMD) model, we study the centrality and evolution time dependence of higher moments of netbaryon distribution in Au + Au collisions at √ sNN = 17.3 GeV. The results suggest that Kurtosis and Skewness are less sensitive to the acceptance effect and late collision process. Thus, they should be good observables providing the information of the early stage of heavy ion collision. In addition, our study shows that the Kurtosis times σ 2 of net-proton distribution are quite different to that of net-baryon when collisions energy is lower than √ sNN = 20 GeV, the Monte Calor calculations on Kurtosis·σ 2 have a deviation from the theoretical predictions.

Momentum-space azimuthal harmonic event planes (EP) are constructed from final-state midrapidity particles binned in transverse momentum (pT ) in √ sNN = 200 GeV Au+Au collisions in a multi-phase transport (AMPT) model. The EP correlations between pT bins, corrected by EP resolutions, are smaller than unity. This indicates that the EP's decorrelate over pT in AMPT, qualitatively consistent with data and hydrodynamic calculations. It is further found that the EP correlations approximately factorize into single pT -bin EP correlations to a common plane. This common plane appears to be the momentum-space EP integrated over all pT , not the configurationspace participant plane (PP).