Event-by-event mean-p t fluctuations from the AMPT model with a dynamical quark coalescence mechanism

Abstract

The event-by-event fluctuations of the mean transverse momentum (p t) in Au + Au collisions at –200 GeV and Pb + Pb collisions at 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 –62.4 GeV. Specially, the relative dynamical mean-p t fluctuation with centrality of 0%–5% can be well reproduced by the DQCM AMPT.