Global Polarization of Ξ and ω Hyperons in Au+Au Collisions at sNN =200 GeV

Abstract

Global polarization of Ξ and ω hyperons has been measured for the first time in Au+Au collisions at sNN=200 GeV. The measurements of the Ξ- and Ξ¯+ hyperon polarization have been performed by two independent methods, via analysis of the angular distribution of the daughter particles in the parity violating weak decay Ξ→Λ+π, as well as by measuring the polarization of the daughter Λ hyperon, polarized via polarization transfer from its parent. The polarization, obtained by combining the results from the two methods and averaged over Ξ- and Ξ¯+, is measured to be ⟨PΞ ©=0.47±0.10(stat)±0.23(syst)% for the collision centrality 20%-80%. The ⟨PΞ.