Axial-Vector and Tensor Spin Polarization and Chiral Restoration in Quark Matter

TL;DR

This paper investigates how axial-vector and tensor interactions induce spin polarization in quark matter within the NJL model, revealing a new phase that influences chiral symmetry restoration at high densities.

Contribution

It introduces a detailed analysis of spin-polarized phases caused by different interactions and their impact on chiral symmetry in quark matter.

Findings

Spin-polarized phases emerge at high densities with strong spin-spin interactions.

These phases extend beyond the chiral restoration density.

A new spontaneous chiral symmetry breaking phase is identified.

Abstract

We study spontaneous spin-polarizations of quark matter with flavour $SU(2)$ symmetry at zero temperature in the NJL model. In a relativistic framework, there are two types of the spin-spin interactions: axial-vector (AV) and tensor (T), which accordingly give rise to different types of spin-polarized materials. When the spin-spin interaction is sufficiently strong, the spin-polarized phase emerges within a specific density region. As the spin-spin interaction becomes stronger, this phase extends over higher density region beyond the critical density of chiral restoration in normal quark matter. We show that the spin-polarized phase leads to another kind of the spontaneous chiral symmetry breaking phase.