UC Riverside

Directed flow (ν1) is a good probe of the early-stage dynamics of collision systems, and the ν1 slope at midrapidity (dv1/dy|y=0) is sensitive to the system's equation of state. STAR has published ν1(y) measurements for ten particle species (π±, p, p‾ Λ Λ‾ ϕ K± and KS0) in Au+Au collisions at eight beam energies from sNN=7.7GeV to200GeV. In this study, we employ a simple coalescence idea to decompose ν1 of hadrons into ν1 of constituent quarks. The dv1/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 sNN=11.5GeV to200GeV, and a sharp deviation from this picture is observed at 7.7 GeV. The dv1/dy of transported quarks is studied via net particles (net p and net Λ). In these proceedings, we further extract the ν1 slopes of produced and transported quarks, assuming that the coalescence sum rule is valid.