Effects of a strong magnetic field on the QCD flux tube

TL;DR

This study uses lattice QCD simulations to examine how external magnetic fields alter the shape and properties of flux tubes, revealing anisotropic effects and changes in confinement behavior.

Contribution

It provides the first detailed lattice simulation analysis of flux tube modifications under magnetic fields with physical quark masses.

Findings

Magnetic fields act as transverse confinement catalysts.

Magnetic fields inhibit longitudinal confinement.

Flux tubes lose axial symmetry when not aligned with the magnetic field.

Abstract

In this work we investigate the effect of an external magnetic field B on the shape of flux tubes in QCD by means of lattice simulations, performed with N_f=2+1 flavors of stout improved dynamical staggered quarks with physical masses. After having discussed some difficulties in the practical definition of the flux tube at B=0, we show that these ambiguities do not affect the determination of the flux tube modifications induced by the magnetic field. Different results are obtained depending on the relative orientations of the flux tube and of the magnetic field: they confirm that the magnetic field acts as transverse confinement catalyser and longitudinal confinement inhibitor; moreover, the flux tube itself loses its axial symmetry when it is not directed along the magnetic background.