Beam-Energy and Centrality Dependence of Directed Flow of Identified Particles

Abstract

These proceedings present directed flow ($v_1$) measurements in Au+Au collisions from STAR's Beam Energy Scan (BES) program at the Relativistic Heavy-Ion Collider, for $p$, $\bar{p}$, $\Lambda$, $\bar{\Lambda }$, $K^{\pm }$, $K_S^0$ and ${\pi }^{\pm }$. At intermediate centrality, protons show a minimum in directed flow slope, $d{v}_1/dy{|}_{y\le 0.8}$, as a function of beam energy. Proton $d{v}_1/dy$ changes sign near 10 GeV, and the directed flow for $\Lambda$ is consistent with the proton result. The directed flow slope for net protons shows a clear minimum at 14.5 GeV and becomes positive at beam energies below 10 GeV and above 30 GeV. New results for net-kaon directed flow slope resemble net protons from high energy down to 14.5 GeV, but remain negative at lower energies. The slope $d{v}_1/dy$ shows a strong centrality dependence, especially for $p$ and $\Lambda$ at the lower beam energies. Available model calculations are in poor agreement.

for the STAR Collaboration

References in corpus (3)

• 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
• Directed flow, a signal for the phase transition in Relativistic Nuclear Collisions?

Cited by in corpus (6)

• The ALICE experiment: a journey through QCD
• Global polarization of $\Lambda$ and $\overline{\Lambda }$ hyperons in Pb-Pb collisions at the LHC
• Sensitivity of the excitation functions of collective flow to relativistic scalar and vector meson interactions in the relativistic quantum molecular dynamics model RQMD.RMF
• Directed flow of $\Lambda$ in high-energy heavy-ion collisions and $\Lambda$ potential in dense nuclear matter
• 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