标题：Directed flow of quarks from the RHIC Beam Energy Scan measured by STAR
作者：Wang, Gang; Adam, J.; Adamczyk, L.; Adams, J. R.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Anderso 更多
作者机构：[Wang, Gang] Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA.; [Drachenberg, J. L.] Abilene Christian Univ, Abilene, TX 79699 更多
会议名称：27th International Conference on Ultrarelativistic Nucleus-Nucleus Collisions (Quark Matter)
会议日期：MAY 13-19, 2018
来源：NUCLEAR PHYSICS A
关键词：heavy-ion collision; directed flow; beam energy scan; coalescence;; transported quark
摘要：Directed flow (v(1)) is a good probe of the early-stage dynamics of collision systems, and the v(1) slope at midrapidity (dv(1)/dy vertical bar(y=0)) is sensitive to the system's equation of state. STAR has published v(1)(y) measurements for ten particle species (pi(+/-), p, (p) over bar, Lambda, (Lambda) over bar, phi, K-+/- and K-S(0)) in Au+Au collisions at eight beam energies from, root 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 dv(1)/dy values of (p) over bar, K- and (Lambda) over bar are used to test the coalescence sum rule for produced quarks. Data involving produced quarks support the coalescence picture at root s(NN) = 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 Lambda). In these proceedings, we further extract the v(1) slopes of produced and transported quarks, assuming that the coalescence sum rule is valid.