Directed flow of quarks from the RHIC Beam Energy Scan measured by STAR

Abstract

Directed flow ($v_1$) is a good probe of the early-stage dynamics of collision systems, and the $v_1$ slope at midrapidity ($d{v}_1/dy{|}_{y=0}$) is sensitive to the system's equation of state. STAR has published $v_1(y)$ measurements for ten particle species (${\pi }^{\pm }$, $p$, $\bar{p}$, $\Lambda$, $\bar{\Lambda }$, $\varphi$, $K^{\pm }$ and $K_S^0$) in Au+Au collisions at eight beam energies from $\sqrt{s_{NN}}=7.7$ GeV to 200 GeV. In this study, we employ a simple coalescence idea to decompose $v_1$ of hadrons into $v_1$ of constituent quarks. The $d{v}_1/dy$ values of $\bar{p}$, $K^{-}$ and $\bar{\Lambda }$ are used to test the coalescence sum rule for produced quarks. Data involving produced quarks support the coalescence picture at $\sqrt{s_{NN}}=11.5$ GeV to 200 GeV, and a sharp deviation from this picture is observed at 7.7 GeV. The $d{v}_1/dy$ of transported quarks is studied via net particles (net $p$ and net $\Lambda$). In these proceedings, we further extract the $v_1$ slopes of produced and transported quarks, assuming that the coalescence sum rule is valid.

4 pages, 5 figures, Quark Matter 2018 proceedings

References in corpus (8)

• Bulk Properties of the Medium Produced in Relativistic Heavy-Ion Collisions from the Beam Energy Scan Program
• Triangularity and Dipole Asymmetry in Heavy Ion Collisions
• Coalescence Models For Hadron Formation From Quark Gluon Plasma
• Beam-Energy Dependence of Directed Flow of $\Lambda$, $\bar{\Lambda }$, $K^{\pm }$, $K_s^0$ and $\varphi$ in Au+Au Collisions
• Examination of the directed flow puzzle in heavy-ion collisions
• Examination of directed flow as a signature of the softest point of the equation of state in QCD matter
• Directed Flow Indicates a Crossover Deconfinement Transition in Relativistic Nuclear Collisions
• Equation of state dependence of directed flow in a microscopic transport model

Cited by in corpus (3)

• Testing the impact of electromagnetic fields on the directed flow of constituent quarks in heavy-ion collisions
• Evidence of Coalescence Sum Rule in Elliptic Flow of Identified Particles in High-energy Heavy-ion Collisions
• Examining the influence of hadronic interactions on the directed flow of identified particles in RHIC Beam Energy Scan energies using UrQMD model