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Volume 347 - Corfu Summer Institute 2018 "School and Workshops on Elementary Particle Physics and Gravity" (CORFU2018) - Session: The Critical Point and Onset of Deconfinement Conference
Directed flow and freeze-out in relativistic heavy-ion collisions at NICA and FAIR energies
L. Bravina,* Y. Kvasiuk, D. Sachenko, S. Y. Sivoklokov, O. Vitiuk, E. E. Zabrodin
*corresponding author
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Published on: 2019 September 19
Directed flow of charged particles is studied in
nucleus-nucleus collisions simulated within the energy range accessible
for NICA and FAIR facilities. Two transport cascade models, UrQMD and
QGSM, are employed. These models use different mechanisms of the string
excitation and string fragmentation. Despite of the differences,
directed flows of charged pions and charged kaons in both models remain
antiflow-oriented with reduction of the collision energy from $\sqrt{s}
= 11.5$~GeV to 3.5~GeV. In contrast, the directed flow of protons
changes its sign from antiflow to normal flow within the investigated
energy interval. Both models favor continuous non-uniform emittence of
hadrons from the expanding fireball rather than sharp, or sudden,
freeze-out picture adopted by majority of hydrodynamic models. We found
that the earlier frozen hadrons carry the strongest directed flow at
midrapidity, although the flow development even at $|y| \leq 0.5$ takes
about 8-12~fm/$c$ for different hadron species.
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