On the topological charge of SO(2) gauged Skyrmions in 2 + 1 and 3 + 1 dimensions

Abstract

The question of the dependence of the topological charge q of a gauged Skyrmion, on the gauge field, is studied quantitatively. Two examples, both gauged with SO(2) are studied and contrasted: i) The O(3) model in 2+1 dimensions, and ii) The O(4) model in 3+1 dimensions. In case i), where the (usual) Chern–Simons (CS) term is present, the value of q changes sign, going through zero. This evolution is tracked by a parameter characterising the solutions in the given theory. In case ii), in which dimensions no CS density is available, the evolution of q is not observed.