$\Lambda$ and $\bar{\Lambda}$ global polarization from the core-corona model

TL;DR

This paper models the global polarization of $ extLambda$ and $ar{ extLambda}$ hyperons in heavy-ion collisions using a core-corona approach, linking polarization features to the source composition and collision energy.

Contribution

It introduces a core-corona model to explain the energy and centrality dependence of hyperon polarization in heavy-ion collisions.

Findings

Polarizations peak at collision energies below 10 GeV.

Peak positions and heights depend on source composition and collision centrality.

Polarization behavior is linked to the relative abundance of hyperons from core and corona.

Abstract

We report on work aimed to describe the $\Lambda$ and $\bar{\Lambda}$ global polarizations in a heavy-ion collision environment using the core-corona model, where the source of these hyperons is a high-density core and a less dense corona. We show that the overall properties of the polarization excitation functions can be linked to the relative abundance of $\Lambda$s and $\bar{\Lambda}$s coming from the core versus those coming from the corona. Both global polarizations peak at collision energies $\sqrt{s_{NN}} \lesssim 10$ GeV. The exact positions and heights of these peaks depend not only on a reversal of relative abundances with collision energy, but also on the centrality class, both related to the QGP volume and lifetime.