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.