Does non-monotonic behavior of directed flow signal the onset of deconfinement?

Abstract

We investigate the effects of nuclear mean-field as well as the formation and decay of nuclear clusters on the directed flow $v_1$ in high energy nucleus-nucleus collisions from $\sqrt{s_{NN}}=7.7$ GeV to 27 GeV incident energies within a transport model. Specifically, we use the JAM transport model in which potentials are implemented based on the framework of the relativistic quantum molecular dynamics. Our approach reproduces the rapidity dependence of directed flow data up to $\sqrt{s_{NN}}\approx 8$ GeV showing the significant importance of mean-field. However, the slopes of $d{v}_1/dy$ at mid-rapidity are calculated to be positive at $\sqrt{s_{NN}}=11.7$ and 19.6 GeV, and becomes negative above 27 GeV. Thus the result from the JAM hadronic transport model with nuclear mean-field approach is incompatible with the data. Therefore within our approach, we conclude that the excitation function of the directed flow cannot be explained by the hadronic degree of freedom alone.

Proceedings of the 25th International Conference on Ultrarelativistic Nucleus-Nucleus Collisions (Quark Matter 2015), Kobe, Japan, 4 pages, 3figures

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• Beam-Energy Dependence of Directed Flow of Protons, Antiprotons and Pions in Au+Au Collisions
• Examination of the directed flow puzzle in heavy-ion collisions
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Cited by in corpus (8)

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• Sensitivity of the excitation functions of collective flow to relativistic scalar and vector meson interactions in the relativistic quantum molecular dynamics model RQMD.RMF
• Beam energy dependence of squeeze-out effect on the directed and elliptic flow in Au+Au collisions at high baryon density region
• Enhancement of elliptic flow can signal a first order phase transition in high energy heavy ion collisions
• Effects of mean-field and the softening of equation of state on elliptic flow in Au+Au collision at $\sqrt{s_{NN}}$ = 5 GeV from JAM model
• Directed flow in heavy-ion collisions and its implications for astrophysics