UCLA

In high-energy heavy-ion collisions, partonic collectivity is evidenced by the constituent quark number scaling of elliptic flow anisotropy for identified hadrons. A breaking of this scaling and dominance of baryonic interactions is found for identified hadron collective flow measurements in s NN = 3 GeV Au+Au collisions. In this paper, we report measurements of the first- and second-order azimuthal anisotropic parameters, v 1 and v 2 , of light nuclei (d, t, 3He, 4He) produced in s NN = 3 GeV Au+Au collisions at the STAR experiment. An atomic mass number scaling is found in the measured v 1 slopes of light nuclei at mid-rapidity. For the measured v 2 magnitude, a strong rapidity dependence is observed. Unlike v 2 at higher collision energies, the v 2 values at mid-rapidity for all light nuclei are negative and no scaling is observed with the atomic mass number. Calculations by the Jet AA Microscopic Transport Model (JAM), with baryonic mean-field plus nucleon coalescence, are in good agreement with our observations, implying baryonic interactions dominate the collective dynamics in 3 GeV Au+Au collisions at RHIC.