Study of Λ polarization in relativistic nuclear collisions at √sNN=7.7 –200 GeV

Abstract

We present a calculation of the global polarization of Λ hyperons in relativistic Au–Au collisions at RHIC Beam Energy Scan range sNN=7.7-200 GeV with a 3 + 1 -dimensional cascade+viscous hydro model, UrQMD+vHLLE. Within this model, the mean polarization of Λ in the out-of-plane direction is predicted to decrease rapidly with collision energy from a top value of about 2% at the lowest energy examined. We explore the connection between the polarization signal and thermal vorticity and estimate the feed-down contribution to Λ polarization due to the decay of higher mass hyperons.