Centrality and transverse momentum dependencies of hadrons in Pb+Pb collisions at $\sqrt{s_{NN}} = 5.02$ TeV and Xe+Xe collisions at $\sqrt{s_{NN}} = 5.44$ TeV from a multi-phase transport model

Abstract.

In this paper, we study and predict the charged-particle pseudorapidity multiplicity density ($\frac{\mathrm{d} N_{ch}}{\mathrm{d}\eta}$), transverse momentum spectra of identified particles and their ratios in relativistic heavy ion collisions at the Large Hadron Collider (LHC), using the string-melting version of a multi-phase transport (AMPT) model with an improved quark coalescence method. We extend this improved AMPT model to the energy region available in the experiment and test its validity, in particular, by predicting the experimental observables. Results of the charged-particle pseudorapidity multiplicity density from AMPT model calculations for Pb+Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV are compared with the experimental data. Good agreements are generally found between the theoretical calculations and experimental data. But for Xe+Xe collisions at $\sqrt{s_{NN}}=5.44$ TeV, the $\frac{\mathrm{d} N_{ch}}{\mathrm{d}\eta}$ are systematically overestimated by 20% at different centralities with the same model parameters. We predict the $p_T$ spectra of charged pions, kaons and protons as well as their ratios $K/\pi$ and $p/\pi$ at midrapidity ($\vert y\vert < 0.5$) in both Pb+Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV and Xe+Xe collisions at $\sqrt{s_{NN}}=5.44$ TeV that are measured at LHC. The $p_T$ spectra of identified particles in Pb+Pb collisions from the improved AMPT model are compared and found to be consistent with results from the iEBE-VISHNU hybrid model with TRENTo initial condition.