Strongly intensive quantities Σ[P T , N] and Δ[P T , N] have become one of the important tools in study of phase transitions and critical points in high energy heavy-ion collisions. In this paper the properties of Σ[P T , N] and Δ[P T , N] are discussed within different colliding nuclei systems generated by the AMPT model. The combined event method are proposed to simulate the model of independent sources in which Σ[P T , N] and Δ[P T , N] are independent of the number of original events. The effects of transverse momentum, pseudorapidity and parton cascade are also discussed.

We present a study of the transverse momentum (pT) spectra and the differential elliptic flow (v2) in a multi-phase transport model based on a dynamical quark coalescence model for Au + Au collisions at and 39 GeV. We have compared our results with the experimental data. The v2 of is found to be sensitive to the size parameter for mesons in the model. Our study indicates that the elliptic flow splitting between p and at lower energies may be partly due to quark coalescence in phase space.

The event-by-event fluctuations of the mean transverse momentum (p t) in Au + Au collisions at s NN = 7.7 –200 GeV and Pb + Pb collisions at s NN = 2.76 T e V are analyzed using a multiphase transport model (AMPT) with a dynamical quark coalescence mechanism (DQCM). The analysis shows that at 19.6 GeV there exists a splitting between the relative dynamical mean-p t fluctuation from the DQCM AMPT and from the original AMPT (i.e., AMPT with string melting) at freeze-out. Based on the hadron information obtained at different stages of nuclear collisions from the AMPT model, we show that this splitting first arises from the quark coalescence hadronization process, and then develops during the resonance decay process. The results are compared with measurements from STAR at the relativistic heavy-ion collider (RHIC) and ALICE at the large hadron collider (LHC). The comparison shows that the relative dynamical mean-p t fluctuation for non-peripheral collisions at 200 GeV and 2.76 TeV can be explained by these two coalescence scenarios. After introducing the DQCM into the AMPT model, the results become slightly larger and appeared to be closer to the experimental data for s NN = 7.7 –62.4  GeV. Specially, the relative dynamical mean-p t fluctuation with centrality of 0%–5% can be well reproduced by the DQCM AMPT.