Speaker
Description
The study of charged-particle production and collective flow in relativistic heavy-ion collisions provides important insight into the properties and space-time evolution of strongly interacting matter. In this work, we investigate the pseudorapidity dependence of charged-particle multiplicity and elliptic flow in Pb+Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV and O+O collisions at $\sqrt{s_{NN}}=5.36$ TeV. Event-by-event initial conditions are generated using the TRENTo model with a three-dimensional entropy-density parametrization and subsequently evolved through relativistic viscous hydrodynamics using the MUSIC framework. Final-state particles are sampled on the freeze-out surface and further propagated through the UrQMD hadronic transport model. The calculated charged-particle pseudorapidity distributions, $dN_{\mathrm{ch}}/d\eta$, are found to reproduce the measured broad midrapidity structure and the decrease toward forward and backward pseudorapidities. The pseudorapidity dependence of the elliptic flow coefficient, $v_2(\eta)$, is also described consistently for Pb+Pb collisions, while predictions are presented for O+O collisions. A comparison of the two systems reveals a clear dependence of particle production and collective flow on the collision-system size. The results indicate that collective behavior remains significant even in the smaller O+O system, demonstrating the applicability of a common three-dimensional initial-state and hydrodynamic framework across different collision systems.