Pion Weak Decay in a Magnetic Field

TL;DR

This paper investigates how a uniform magnetic field affects pion decay width using chiral perturbation theory and compares it with lattice QCD results, highlighting agreement at high fields and discrepancies at low fields.

Contribution

It provides a theoretical calculation of pion decay in magnetic fields and compares it with lattice QCD, identifying the role of decay constants in observed differences.

Findings

Agreement between theory and lattice QCD at large magnetic fields.

Discrepancies at weak magnetic fields are mainly due to differences in decay constants.

The study enhances understanding of pion decay behavior under magnetic influences.

Abstract

Pion decay width in a uniform magnetic background, constructed within chiral perturbation theory, is compared with lattice QCD for which results are available in the muon channel. While the results are consistent for large magnetic fields, the discrepancy observed for weak magnetic fields is largely due to differences in the pion decay constants.