Polarization probes of vorticity in heavy ion collisions

TL;DR

This paper explores how polarization measurements of particles in ultrarelativistic nuclear collisions can reveal detailed information about the system's initial conditions, evolution, and properties, aiding understanding of quark-gluon plasma dynamics.

Contribution

It demonstrates the sensitivity of polarization observables to various stages and parameters of heavy ion collision evolution, proposing experimental strategies for detailed system analysis.

Findings

Polarization is sensitive to initial conditions and system evolution.

Different polarization measurements can disentangle contributing factors.

Energy and rapidity scans may reveal changes in system properties.

Abstract

We discuss the information that can be deduced from a measurement of particle (hyperon or vector meson) polarization in ultrarelativistic nuclear collisions. We describe the sensitivity of polarization to initial conditions, hydrodynamic evolution and mean free path, and find that the polarization observable is sensitive to all details and stages of the system's evolution. We suggest that an experimental investigation covering production plane and reaction plane polarizations, as well as the polarization of jet-associated particles in the plane defined by the jet and particle direction, can help in disentangling the factors contributing to this observable. Scans of polarization in energy and rapidity might also point to a change in the system's properties.