The quantitative behavior of $\alpha$-Yang-Mills-Higgs fields on surfaces

Abstract

We investigate the blow-up behavior of $\alpha$-Yang--Mills--Higgs ($\alpha$-YMH) fields over closed Riemannian surfaces with the target fiber $F = S^{K-1} \subset \mathbb{R}^K$ being the round sphere, focusing on the establishment of the $\alpha$-energy identity and the no-neck property during the bubbling process. A central innovation is the identification of a hidden Jacobian structure through Hodge decomposition and a new conservation law. Furthermore, we derive a Pohozaev-type identity for $\alpha$-YMH fields, which enables refined control of the energy density. Together, these advances ensure the validity of the $\alpha$-energy identity as $\alpha \to 1$. Our analysis further sharpens the Lorentz space estimates from the $L^{2,\infty}$ to the optimal $L^{2,1}$ scale, ultimately yielding the no-neck property in the blow-up regime. These results provide a unified and quantitative framework for understanding singularity formation in variational gauge theories.