Spectral function for pions in magnetic field

TL;DR

This paper investigates how magnetic fields, temperature, and chiral symmetry affect the spectral functions of neutral and charged pions using the NJL model, revealing complex structures and stability behaviors.

Contribution

It provides a detailed analysis of pion spectral functions in magnetic fields, incorporating Landau levels, cuts, and thermal effects within the NJL framework, highlighting new features in meson properties.

Findings

Landau levels cause multi-peak structures in $c0_0$ spectral functions.

Chiral restoration influences peak shifts and enhancements.

Charged pions exhibit damping effects and increased stability at higher temperatures.

Abstract

This study examines the spectral functions of neutral ($\pi_0$) and charged ($\pi_{\pm}$) pions under a uniform magnetic field using the SU(2) Nambu-Jona-Lasinio (NJL) model with the Ritus method. The analysis highlights the complex interplay of magnetic field effects, thermal influences, and chiral symmetry on meson properties in extreme QCD environments. For $\pi_0$, whose properties are governed by the behavior of its constituent quarks, magnetic field-induced Landau levels lead to a multi-peak structure in its spectral function, reflecting stable and resonance solutions that evolve with temperature, showing shifts and critical enhancements near chiral restoration. For $\pi_{\pm}$, cross terms that come from the asymmetry between the constituent quarks introduce Landau cuts alongside Unitary cuts, indicating damping effects, with decay widths narrowing at higher temperatures, suggesting increased stability.