Elliptic Flow in Heavy-Ion Collisions at Energies $\sqrt{s_{NN}}=$ 2.7--39 GeV

Understand

The transverse-momentum integrated elliptic flow of charged particles at midrapidity, $v_2$(charged), and that of identified hadrons from Au+Au collisions are computed in a wide range of incident energies 2.7 GeV $\le \sqrt{s_{NN}}\le$ 39 GeV.

• The simulations are performed within a three-fluid model employing three different equations of state (EoS's): a purely hadronic EoS and two versions of the EoS involving the deconfinement transition---a first-order phase transition and a smooth crossover one.
• The present simulations demonstrate low sensitivity of $v_2$(charged) to the EoS.
• All considered scenarios equally well reproduce recent STAR data on $v_2$(charged) for mid-central Au+Au collisions and properly describe its change of sign at the incident energy decrease below $\sqrt{s_{NN}}\approx$ 3.5 GeV.