Polarization in heavy ion collisions: a theoretical review

Abstract

In these proceedings I discuss the recent progress in the theory of spin polarization in relativistic fluids. To date, a number of studies have begun to examine the impact of the shear tensor on the local spin polarization and whether this contribution can restore agreement between the measurements and the predictions obtained from a polarization induced by the gradients of the plasma. I present the derivation of the spin polarization vector of a fermion at local thermal equilibrium and I discuss the role of pseudo-gauge transformations and of dissipative effects. I list what we can learn from the polarization measured at lower energies. Finally, I discuss possible applications of spin polarization measurements in relativistic heavy ion collisions.

9 pages. Presented at the 20th International Conference on Strangeness in Quark Matter (SQM 2022)

References in corpus (31)

• Angular momentum conservation in heavy ion collisions at very high energy
• Shear-induced spin polarization in heavy-ion collisions
• Fate of spin polarization in a relativistic fluid: An entropy-current analysis
• Local polarization and isothermal local equilibrium in relativistic heavy ion collisions
• Spin-thermal shear coupling in a relativistic fluid
• Spin Hydrodynamics and Symmetric Energy-Momentum Tensors -- A current induced by the spin vorticity --
• Relativistic spin hydrodynamics with torsion and linear response theory for spin relaxation
• Spin polarization induced by the hydrodynamic gradients
• Non-dissipative second-order transport, spin, and pseudo-gauge transformations in hydrodynamics
• From Chiral Kinetic Theory To Relativistic Viscous Spin Hydrodynamics
• Derivation of the nonlocal collision term in the relativistic Boltzmann equation for massive spin-1/2 particles from quantum field theory
• Dissipative Spin Dynamics in Relativistic Matter
• The ideal relativistic spinning gas: polarization and spectra
• Spin tensor and pseudo-gauges: from nuclear collisions to gravitational physics
• Reexamination of local spin polarization beyond global equilibrium in relativistic heavy ion collisions
• Local and global polarization of $\Lambda$ hyperons across RHIC-BES energies: the roles of spin hall effect, initial condition and baryon diffusion
• Exact equilibrium distributions in statistical quantum field theory with rotation and acceleration: scalar field
• Exact equilibrium distributions in statistical quantum field theory with rotation and acceleration: Dirac field
• Hyperon Polarization from the Vortical Fluid in Low Energy Nuclear Collisions
• Pseudo-gauges and relativistic spin hydrodynamics for interacting Dirac and Proca fields
• Pseudogauge dependence of the spin polarization and of the axial vortical effect
• Spin Polarization Formula for Dirac Fermions at Local Equilibrium
• Effect of thermal shear on longitudinal spin polarization in a thermal model
• Spin relaxation rate for heavy quarks in weakly coupled QCD plasma
• New Developments in Relativistic Fluid Dynamics with spin
• Λ polarization from thermalized jet energy
• Pseudo-gauge dependence of quantum fluctuations of energy in a hot relativistic gas of fermions
• Evolution of $\Lambda$ polarization in the hadronic phase of heavy-ion collisions
• Anomalous gravitomagnetic moment and non-universality of the axial vortical effect at finite temperature
• Global $\Lambda$ polarization in heavy-ion collisions at energies 2.4--7.7 GeV: Effect of Meson-Field Interaction
• Helicity polarization in relativistic heavy ion collisions

Cited by in corpus (1)

• Spin polarization induced by magnetic field and the relativistic Barnett effect