Global polarization of $\Lambda$ hyperons in hot QCD matter at TeV energies

TL;DR

This paper investigates the global spin polarization of $\\Lambda$ hyperons in high-energy heavy-ion collisions using relativistic hydrodynamics, revealing insights into the vortical structure of quark-gluon plasma and comparing results with experimental data.

Contribution

It introduces a second-order viscous hydrodynamic model incorporating vorticity and magnetic fields to analyze hyperon polarization in relativistic collisions.

Findings

Qualitative agreement with ALICE measurements at LHC energies.

Quantified contributions of thermal vorticity and magnetic fields to polarization.

Explored the relationship between magnetic and rotational effects on spin polarization.

Abstract

The study of spin polarization of $\Lambda$ hyperons in ultrarelativistic heavy-ion collisions provides insights into the angular momentum and vortical structure of the possible existence of QGP. The present study examines the global spin polarization of $\Lambda$ hyperons using a second-order relativistic viscous hydrodynamic framework that incorporates medium vorticity, shear viscosity, and evolving magnetic fields. It explores thermal vorticity evolution in relativistic heavy-ion collisions and evaluates its value at the decoupling isothermal freeze-out surface. We quantify the contributions of thermal vorticity and magnetic field to the global spin polarization of $\Lambda$ hyperons. Comparing results with recent ALICE measurements in Pb+Pb collisions at $\sqrt{s_{NN}}$ = 2.76 and 5.02 TeV shows qualitative agreement, offering new insights into the vortical structure of QCD matter. It also explores the relationship between magnetic and rotational dynamics, with implications for spin polarization at RHIC and LHC energies.