Domain-Wall Skyrmion Phase in Dense QCD at Strong Magnetic Fields Using Leading-Order Chiral Perturbation Theory

Abstract

Low-energy dynamics of QCD can be described by pion degrees of freedom in terms of the chiral perturbation theory. A chiral soliton lattice, an array of solitons, is the ground state due to the chiral anomaly in the presence of a magnetic field larger than a certain critical value at finite density. Here, we show in a model-independent and fully analytic manner (at the leading order of the chiral perturbation theory) that the chiral soliton lattice phase transits to a “domain-wall skyrmion phase” when the chemical potential is larger than the critical value μc=16πfπ2/3mπ∼1.03GeV with the pion’s decay constant fπ and mass mπ, which can be regarded as the nuclear saturation density. There spontaneously appear stable two-dimensional skyrmions or lumps on a soliton surface, which can be viewed as three-dimensional skyrmions carrying even baryon numbers from the bulk. They behave as superconducting rings with persistent currents due to a charged pion condensation. This phase is in scope of future heavy-ion collider experiments. Published by the American Physical Society 2025