UC Riverside

Directed flow (ν 1) is a good probe of the early-stage dynamics of collision systems, and the ν 1 slope at midrapidity ( d v 1 / d y | y = 0 ) is sensitive to the system's equation of state. STAR has published ν 1(y) measurements for ten particle species ( π ± , p, p ‾ , Λ, Λ ‾ , ϕ, K ± and K S 0 ) in Au+Au collisions at eight beam energies from s N N = 7.7 GeV to 200 GeV . In this study, we employ a simple coalescence idea to decompose ν 1 of hadrons into ν 1 of constituent quarks. The dv 1/dy values of p ‾ , K − and Λ ‾ are used to test the coalescence sum rule for produced quarks. Data involving produced quarks support the coalescence picture at s N N = 11.5 GeV to 200 GeV , and a sharp deviation from this picture is observed at 7.7 GeV. The dv 1/dy of transported quarks is studied via net particles (net p and net Λ). In these proceedings, we further extract the ν 1 slopes of produced and transported quarks, assuming that the coalescence sum rule is valid.