Beam-energy and collision-system dependence of the linear and mode-coupled flow harmonics from STAR

Abstract

Recent measurements and hydrodynamic model calculations suggest that the higher-order flow coefficients ν4 and ν5 have two contributions: a linear contribution driven by the initial-state eccentricities, εn, and a mode-coupled contribution derived from the lower-order eccentricity coefficients ε2 and ε3. Measurements of these two contributions to ν4 and ν5 provide crucial insights to discern initial-state models and to constrain the temperature-dependent specific shear viscosity, η/s, of the plasma produced in heavy-ion collisions. In this work, we have employed the two-subevents cumulant technique to provide the first beam-energy and collision-system dependence of the linear and mode-coupled contributions to the higher-order flow harmonics. Our results are shown and discussed for several centrality intervals for U+U collisions at sNN=193GeV, Au+Au collisions at sNN=200,and54.4GeV and Cu+Au collisions at sNN=200GeV. The results are compared with similar studies performed by the ALICE experiment at LHC.