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

Adamczyk L. AGH University of Science and Technology, Poland
Lednický Richard, promovaný fyzik DrSc. dr. h. c. Institute of physics of the ASCR, JINR Dubna
et al.  different institutions


Scientific journal


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.

Cite article as:
L. Adamczyk, R. Lednický, . et al., "Directed flow of quarks from the RHIC Beam Energy Scan measured by STAR", NUCLEAR PHYSICS A 982 415-418 (2019)