Global polarization in heavy-ion collisions based on axial vortical effect

TL;DR

This paper models the global polarization of hyperons in heavy-ion collisions using the axial vortical effect, achieving good agreement with experimental data and making predictions for future experiments.

Contribution

It introduces a simulation approach based on three-fluid dynamics and equations of state with deconfinement transition to explain hyperon polarization.

Findings

Good agreement with STAR data for polarization and splitting

Suppression of gravitational-anomaly contribution aligns with lattice QCD

Predictions for lower energy collisions to test the model

Abstract

Global polarization of $\Lambda$ and $\bar{\Lambda}$ is calculated based on the axial vortical effect (AVE). Simulations are performed within the model of the three-fluid dynamics. Equations of state with the deconfinement transition result in a good agreement with STAR data for both $\Lambda$ and $\bar{\Lambda}$ polarization, in particular, with the $\Lambda$-$\bar{\Lambda}$ splitting. Suppression of the gravitational-anomaly contribution required for the data reproduction is in agreement with predictions of the QCD lattice simulations. Predictions for the global polarization in forthcoming experiments at lower collision energies are made. These forthcoming data will provide a critical test for the AVE and thermodynamic mechanisms of the polarization.