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

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.

Comments: 4 pages, 3 figures, discussion added, version published in PRC