Hyperon--anti-hyperon polarization asymmetry in relativistic heavy-ion collisions as an interplay between chiral and helical vortical effects

Abstract

We argue that the enhancement in the spin polarization of anti-hyperons compared to the polarization of the hyperons in noncentral relativistic heavy-ion collisions arises as a result of an interplay between the chiral and helical vortical effects. The chiral vortical effect generates the axial current of quarks along the vorticity axis while the recently found helical vortical effect generates the helicity flow -- the projection of the quark's polarization vector onto its momentum -- along the same axis. For massless fermions, the helical charge corresponds to a difference in the contributions of particles and anti-particles to the axial charge. Assuming that the spin of light quarks transfers to the strange quarks via the vector kaon states ("the spin-vector dominance"), we are able to describe the ratio of the (anti)hyperon spin polarizations, obtained by the STAR group, without fitting parameters. We also argue that the helical vortical effect dominates over the chiral vortical effect and the chiral magnetic effect in the generation of the electric current.

9 pages, 3 figures; v2: discussions expanded, chiral magnetic effect and helical vortical effect are compared

References in corpus (4)

• Viscosity Information from Relativistic Nuclear Collisions: How Perfect is the Fluid Observed at RHIC?
• Shear-induced spin polarization in heavy-ion collisions
• Spin-thermal shear coupling in a relativistic fluid
• Different space-time freeze-out picture -- an explanation of different $\Lambda$ and $\bar{\Lambda }$ polarization?

Cited by in corpus (14)

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• Hydrodynamic helicity polarization in relativistic heavy ion collisions
• Relativistic hydrodynamics with spin in the presence of electromagnetic fields
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• Anomalous magnetohydrodynamics with temperature-dependent electric conductivity and application to the global polarization
• Spin polarization induced by magnetic field and the relativistic Barnett effect
• Fast kinetic simulator for relativistic matter
• Shear-induced anomalous transport and charge asymmetry of triangular flow in heavy-ion collisions
• Vortical waves in a quantum fluid with vector, axial, and helical charges. I. Non-dissipative transport
• Helical Separation Effect and helical heat transport for Dirac fermions
• Polarization Dynamics in Paramagnet of Charged Quark-Gluon Plasma
• Vortical waves in a quantum fluid with vector, axial and helical charges. II. Dissipative effects