Diamagnetic and Paramagnetic Phases in Low-Energy Quantum Chromodynamics

TL;DR

This paper investigates the diamagnetic and paramagnetic phases in low-energy QCD using chiral perturbation theory, analyzing how magnetization and susceptibility depend on temperature and magnetic field, complementing lattice QCD results.

Contribution

It provides a systematic low-energy analysis of magnetic phases in QCD, including pion interactions, filling a gap in understanding the pion-dominated regime.

Findings

Magnetic susceptibility varies non-monotonically with temperature and magnetic field.

The study reveals the interplay between diamagnetic and paramagnetic behaviors in low-energy QCD.

Results complement existing lattice QCD studies at different regimes.

Abstract

While it is known that the QCD vacuum in a magnetic background exhibits both diamagnetic and paramagnetic characteristics in the low-energy domain, a systematic investigation of the corresponding phases emerging in the pion-dominated regime is still lacking. Here, within two-flavor chiral perturbation theory, taking into account the pion-pion interaction, we analyze the subtle interplay between zero- and finite-temperature portions in the magnetization and magnetic susceptibility. The dependence of the magnetic susceptibility on temperature and magnetic field strength in the paramagnetic and diamagnetic phase is non-monotonic. Our low-energy analysis complements lattice QCD that is currently operating at higher temperatures and stronger magnetic fields.