Background magnetic field stabilizes QCD string against breaking

TL;DR

This paper predicts that a strong background magnetic field can prevent QCD string breaking in certain directions, potentially leading to a new confining phase and observable effects in heavy-ion collisions.

Contribution

It introduces the concept that magnetic fields above a critical strength can stabilize QCD strings against breaking, revealing a novel phase of confinement.

Findings

String breaking is suppressed above a critical magnetic field.

A new asymmetrically confining phase may form at strong magnetic fields.

Potential experimental signatures include increased u-quark rich hadrons.

Abstract

The confinement of quarks in hadrons occurs due to formation of QCD string. At large separation between the quarks the QCD string breaks into pieces due to light quark-antiquark pair creation. We argue that there exist a critical background magnetic field e B ~ 16 m_\pi^2, above which the string breaking is impossible in the transverse directions with respect to the axis of the magnetic field. Thus, at strong enough magnetic field a new, asymmetrically confining phase may form. The effect - which can potentially be tested at LHC/ALICE experiment - leads to abundance of u-quark rich hadrons and to excess of radially excited mesons in the noncentral heavy-ion collisions compared to the central ones.