Hydrodynamic modeling of the deconfinement phase transition in heavy-ion collisions in the NICA–FAIR energy domain

Abstract

We use (3 $+$ 1) dimensional ideal hydrodynamics to describe the space-time evolution of strongly interacting matter created in Au $+$ Au and Pb $+$ Pb collisions. The model is applied for the domain of bombarding energies 1--160 GeV/nucleon which includes future NICA (Dubna) and FAIR (Darmstadt) experiments. Two equations of state are used, the first one corresponding to resonance hadron gas and the second one including the deconfinement phase transition. The initial state is represented by two Lorentz-boosted nuclei. Dynamic trajectories of matter in the central box of the system are analyzed. They can be well represented by a fast shock-wave compression followed by a relatively slow isentropic expansion. The parameters of collective flows and hadronic spectra are calculated under assumption of the isochronous freeze-out. It is shown that the deconfinement phase transition leads to broadening of proton rapidity distributions, increase of elliptic flows, and formation of the directed antiflow in the central rapidity region. These effects are most pronounced at bombarding energies around 10 GeV/nucleon, when the system spends the longest time in the mixed phase. From the comparison with three-fluid calculations we conclude that the transparency effects are not so important in central collisions at NICA--FAIR energies (below 30 GeV/nucleon).