Meson Octet in a Uniform Magnetic Field

TL;DR

This paper uses chiral perturbation theory to calculate how meson octet masses and decay constants are affected by a uniform magnetic field, providing new theoretical insights and consistency checks.

Contribution

It presents the first detailed calculation of magnetic field effects on meson octet masses and decay constants at next-to-leading order in chiral perturbation theory.

Findings

Neutral pion mass decreases with magnetic field.

Charged meson masses change identically in the magnetic background.

All decay constants increase monotonically with magnetic field.

Abstract

Chiral perturbation theory is utilized to construct the renormalized magnetic masses and decay constants of the meson octet at next-to-leading order. While the neutral pion mass decreases identically to two-flavor chiral perturbation theory, the neutral kaon mass remains unaltered by the magnetic field. The renormalized magnetic masses for the charged mesons change identically. Meson decay constants in the axial and vector channels are constructed. Each of the decay constants increase monotonically in the magnetic background. Low-energy theorems -- Gell-Mann-Oakes-Renner relations for the neutral mesons and their generalization for the charged mesons through the pseudoscalar coupling -- are constructed and provide non-trivial crosschecks.