Gauge Symmetry Breaking in the Asymptotic Analysis of Self Dual Yang-Mills-Higgs $SU(2)$ Monopoles

Abstract

We consider the $SU(2)$ Self-Dual Yang Mills Higgs Lagrangian in 3 dimension. By adding a ''Gauge Mass'' term to this YMH Lagrangian in the form of $L^2$ norm of the connection we break the gauge invariance and critical points are automatically fulfilling globally the Coulomb condition. We study the so called ``large mass asymptotic'', which has the effect of ''squeezing'' the monopoles. For any unit Higgs field data at the boundary we prove that minimizers of this Coulomb-Yang-Mills-Higgs Functional converge to harmonic maps into ${\mathbb S}^2$ extending this data. This asymptotic moreover is subject to concentration conpactness phenomena and the convergence is strong away from a 1 dimensional rectifiable closed concentration set. Then we prove that, having chosen a large enough coupling constant, the limiting minimal energy is converging towards the minimal Brezis-Coron-Lieb relaxed harmonic map energy for this boundary data. In the second part of the paper we examine a different asymptotic regime characterised by overloading monopoles. In this regime we prove that asymptotically, the magnetic field becomes exclusively longitudinal with a $U(1)$ abelian component along the Higgs Field while the Higgs field itself converges to a smooth absolute minimizer of a relaxation of the Faddeev-Skyrme functional of maps from ${\mathbb B}^3$ into ${\mathbb S}^2$. In the third part of the paper we study the behaviour of these configurations when the parameter in front of the Fadeev-Skyrme component respectively goes to zero and $+\infty$. In the first case one recovers the Brezis Coron Lieb relaxed energy at the limit while in the second case the minimal limiting energy is converging towards the minimal Dirichlet energy of maps into ${\mathbb S}^3$ whose projection by the Hopf fibration is equal to the fixed boundary data.