# Spontaneous Spin Polarization due to Tensor Selfenergies in Quark Matter

## TL;DR

This paper investigates how tensor interactions influence spin polarization in quark matter within the NJL model, revealing persistent spin-polarized phases even at zero quark mass and identifying two distinct phases related to chiral symmetry states.

## Contribution

It demonstrates the existence of spin-polarized phases driven by tensor interactions in quark matter, including phases that persist at zero quark mass and are independent of interaction strength.

## Key findings

- Spin-polarized phase persists at zero quark mass.
- Two types of spin-polarized phases identified.
- Spin polarization can occur independently of tensor interaction strength.

## Abstract

We study the magnetic properties of quark matter in the NJL model with the tensor interaction. The spin-polarized phase given by the tensor interaction remains even when the quark mass is zero, while the phase given by the axial vector interaction disappears. There are two kinds of spin-polarized phases: one appears in the chiral-broken phase, and the other appears in the chiral-restored phase where the quark mass is zero. The latter phase can appear independently of the strength of the tensor interaction.