Physical Review Letters
Rapidity-odd directed flow (v1) measurements for charged pions, protons, and antiprotons near midrapidity (y= 0) are reported in √ˢᴺᴺ = 7.7, 11.5, 19.6, 27, 39, 62.4, and 200 GeVAu+Au collisions as recorded by the STAR detector at the Relativistic Heavy Ion Collider. At intermediate impact parameters, the proton and net-proton slope parameter d v1/ d y│y=0 shows a minimum between 11.5 and 19.6 GeV. In addition, the net-proton d v1/ d y│y=0 changes sign twice between 7.7 and 39 GeV. The proton and net-proton results qualitatively resemble predictions of a hydrodynamic model with a first-order phase transition from hadronic matter to deconfined matter, and differ from hadronic transport calculations.
Original Publication Citation
Adamczyk, L., Adkins, J. K., Agakishiev, G., Aggarwal, M. M., Ahammed, Z., Alekseev, I., . . . Collaboration, S. (2014). Beam-energy dependence of the directed flow of protons, antiprotons, and pions in Au+Au collisions. Physical Review Letters, 112(16), 7. doi:10.1103/PhysRevLett.112.162301
Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Koralt, I.; and STAR Collaboration, "Beam-Energy Dependence of the Directed Flow of Protons, Antiprotons, and Pions in Au+Au Collisions" (2014). Physics Faculty Publications. 161.