2019 Volume 74 Issue 10 Pages 727-732
The matter created in non-central heavy-ion collisions should have an initial orbital angular momentum carried by the two colliding nuclei. This angular momentum would be partially transferred to the spin of produced particles due to spin-orbit coupling, leading to the global polarization. The STAR Collaboration observed global polarizations of Λ and Λ(¯) hyperons in Au+Au collisions for collision energies of √SNN=7.7–200 GeV, indicating the creation of the most vortical fluid ever observed, with vorticity of the order of ω~1022 s-1. In this article, we review recent results on the polarization measurements and discuss the physics implications.