Global hyperon polarization and effects of decay feeddown

Abstract

We study the global polarizations of Λ, Ξ−, and Ω− hyperons in noncentral Au + Au collisions at √SNN = 7.7-200 GeV$\sqrt {{S_{{\rm{NN}}}}} = 7.7 - 200\,{\rm{GeV}}$SNN=7.7−200 GeV. We highlight the importance of effect of decay feeddown to the measured global polarization. With the decay contributions taken into account, the global polarization ordering PΩ− > PΞ− > PΛ${P_{{\Omega ^ - }}} > {P_{{\Xi ^ - }}} > {P_\Lambda }$PΩ−>PΞ−>PΛ can be naturally explained, which is consistent with the observation recently reported from the STAR experiment from Au+Au collisions at 200 GeV. We also extend our calculations to predict expectations from the RHIC-BES II data.