Light- and hyper-nuclei collectivity in Au+Au collisions at RHIC-STAR

We report the first results on collision energy and particle mass dependence of directed flow v1 of light- and hyper-nuclei in mid-central Au+Au collisions at center of mass energies per nucleon pair of 3.0, 3.2, 3.5, and 3.9 GeV. All data have been collected by the STAR experiment in the fixed-target mode during the second phase of the RHIC beam energy scan. The mid-rapidity v1 slope, dv1/dy|y=0, of hyper-nuclei shows a similar energy and particle mass dependence to that of light-nuclei. The results suggest that the coalescence mechanism plays a dominant role in the formation of light- and hyper-nuclei.