Λ0 polarization in ultrarelativistic nucleus-nucleus collisions

We study the polarization of Λ0’s produced in ultrarelativistic heavy-ion collisions. We argue that when the density of participants in the reaction is below the critical value for the production of a Quark-Gluon Plasma (QGP), recombination processes dominate the Λ0 production cross section and hence, Λ0’s are polarized. However, when the density of participants is above the critical value for QGP formation, coalescence processes dominate Λ0 production, giving rise to a reduction in the Λ0 polarization. For densities below the critical density for QGP production, we describe Λ0 polarization in terms of the DeGrand-Miettinen model and correct for the effects introduced by multiple scattering of the produced Λ0 within the nuclear environment.