  We report on the core-corona model developed to describe the main features of
hyperon global polarization in semicentral relativistic heavy-ion collisions as
a function of the collision energy. We first neglect the contribution to
polarization from hyperons produced in the corona. In this scenario, the global
polarization turns out to be described by a delicate balance between the
vorticity-to-spin transferring reactions in the core and the predominance of
corona over core matter at low energies. We show how this last feature provides
a key ingredient missing in our original model that helps to better describe
the excitation function for $\Lambda$ and $\overline{\Lambda}$ global
polarization. To improve the description, we then introduce the contribution to
the global polarization coming from the transverse polarization of $\Lambda$s
produced in the corona, which is hereby assumed to be similar to the well-known
polarization produced in p + p reactions. The results show a small positive
contribution to the global polarization, however they are not yet conclusive
due to the small size of the MC sample used in the analysis.
