Neutral pseudoscalar and vector meson masses under strong magnetic fields in an extended NJL model: mixing effects

TL;DR

This paper investigates how external magnetic fields influence the mass spectrum of light neutral mesons using an extended NJL model, highlighting mixing effects that significantly alter meson masses.

Contribution

It introduces an extended NJL model with flavor mixing and studies the impact of magnetic fields on meson masses, comparing results with lattice QCD data.

Findings

Magnetic fields cause mixing effects that reduce the lightest meson mass.

The model's predictions align with lattice QCD results.

Pseudoscalar-vector mixing significantly influences meson mass shifts.

Abstract

Mixing effects on the mass spectrum of light neutral pseudoscalar and vector mesons in the presence of an external uniform magnetic field $\vec B$ are studied in the framework of a two-flavor NJL-like model. The model includes isoscalar and isovector couplings both in the scalar-pseudoscalar and vector sectors, and also incorporates flavor mixing through a 't Hooft-like term. Numerical results for the $B$ dependence of meson masses are compared with present lattice QCD results. In particular, it is shown that the mixing between pseudoscalar and vector meson states leads to a significant reduction of the mass of the lightest state. The role of chiral symmetry and the effect of the alignment of quark magnetic moments in the presence of the magnetic field are discussed.