Anisotropic (v₁ and v₂) Flow in Relativistic Heavy-Ion Collisions at Energies between 4 GeV and 200 GeV

Abstract

Basic features of directed and elliptic flows of identified hadrons in heavy-ion collisions at intermediate and high energies are considered within two transport string models, UrQMD and QGSM. Both models indicate changing of the sign of proton directed flow at midrapidity from antiflow to normal flow with decreasing energy of collisions. The origin of this effect is traced to hadron rescattering in baryon-rich remnants of the colliding nuclei. To distinguish the effect of rescattering from the flow softening caused by creation of quark-gluon plasma one has to compare heavy-ion and light-ion collisions at the same energy. Both directed and elliptic flows at midrapidity are formed within t = 10-12 fm/c. The differences in the development of elliptic flows of mesons and baryons are found at high energies. These differences can be explained by dissimilar freeze-out conditions, thus suggesting simultaneous study of particle collective flow and freeze-out.

Directed Flow in Microscopic Models in Relativistic A+A Collisions

“…Moreover, transition from antiflow to normal flow occurs earlier (in energy scale) in heavy-ion collisions compared to the light-ion ones. The explanation of this effect is as follows [22][23][24][25]. Hadrons are produced more copiously in heavy-ion collisions than in light-ion collisions at the same centrality range.…”

Directed flow and freeze-out in relativistic heavy-ion collisions at NICA and FAIR energies

“…To investigate the basic features of the directed flow of pions and protons in UrQMD and QGSM we choose four bombarding energies, √ s = 3.5 GeV, 5.5 GeV, 7.7 GeV and 19.6 GeV, two systems of colliding nuclei, Au+Au and Xe+Xe (as planed for NICA), and three centrality intervals, proposed by the STAR collaboration, σ /σ geo = 0 − 10%, 10 − 40% and 40 − 80%. The material presented below has been partially shown at the conferences QUARKS'18 [18] and ICNFP'2018 Figure 2: The same as Fig. 1 but for the directed flow of charged pions.…”