Global spin polarization of multistrange hyperons and feed-down effect in heavy-ion collisions

Global spin polarization of hyperons is an important observable to probe the vorticity of the quark-gluon plasma produced in heavy-ion collisions. We calculate the global polarizations of Λ, Ξ−, and Ω− in Au+Au collisions at energies sNN= 7.7–200 GeV based on a multiphase transport model. Our calculations suggest that their primary global polarizations fulfill PΩ−≃5/3PΞ−≃5/3PΛ. We also estimate the feed-down effect of particle decay on the global polarization. With the feed-down effect taken into account, the global polarizations of Λ and Ξ− are clearly separated, and the final global polarizations are in the ordering: PΩ−>PΞ−>PΛ. Such a relation can be tested in experiments, which will provide us more information about the global polarization mechanism.