Vorticity and particle polarization in heavy ion collisions (experimental perspective)

TL;DR

This paper reviews recent experimental measurements of vorticity and particle polarization in heavy ion collisions, discusses their connection to chiral effects, and outlines future experimental directions for mapping vorticity fields.

Contribution

It provides an overview of experimental results on polarization, explores their theoretical connection to chiral anomalies, and suggests new experimental approaches for detailed vorticity mapping.

Findings

Global polarization measurements indicate significant vorticity in heavy ion collisions.

The Blast Wave model estimates show anisotropic flow influences vorticity components.

Potential circular vorticity patterns may exist in asymmetric collisions like Cu+Au.

Abstract

The recent measurements of the global polarization and vector meson spin alignment along the system orbital momentum in heavy ion collisions are briefly reviewed. A possible connection between the global polarization and the chiral anomalous effects is discussed along with possible experimental checks. Future directions, in particular those aimed on the detailed mapping of the vorticity fields, are outlined. The Blast Wave model is used for an estimate of the anisotropic flow effect on the vorticity component along the beam direction. We also point to a possibility of a circular pattern in the vorticity field in asymmetric, e.g. Cu+Au, central collisions.