The large mass limit of $G_2$ and Calabi-Yau monopoles
Yang Li
TL;DR
This work analyzes the large mass limit of $SU(2)$ G$_2$-monopoles and Calabi–Yau monopoles on asymptotically conical manifolds. By decomposing the curvature into parallel and perpendicular parts and establishing a suite of sharp estimates (monotonicity, $\epsilon$-regularity, Higgs-field decay, and exponential decay of $F^{\perp}$), the authors show curvature concentrates along a calibrated cycle $Q$, while the generic region collapses to an abelian $U(1)$ monopole. A mollified Chern form and a Whitney/deformation framework yield a weak limit data $(F_{\infty},\Phi_{\infty},Q)$ with $Q$ an integral coassociative (resp. SLag) current; the limit charges a singular abelian monopole on $M\setminus\mathrm{supp}(Q)$ and an energy identity equates the limiting energy to contributions from monopole bubbles along normal fibers. The results provide a rigorous gauge-theoretic realization of the Donaldson–Segal program, linking large-mass monopoles to calibrated geometry and offering a nonperturbative mechanism for the appearance of coassociative and special Lagrangian cycles with integral multiplicities. The framework also highlights intricate bubbling phenomena and multiple open problems, including multivalued Fueter sections and extensions to general Lie groups.
Abstract
We develop a structure theory for the limit of $SU(2)$ $G_2$-monopoles (resp. Calabi-Yau monopoles) on a principal $SU(2)$-bundle over an asymptotically conical $G_2$-manifolds (resp. Calabi-Yau 3-folds) as the mass parameter tends to infinity, while the topologial data for the bundle stays fixed. We show how to extract a singular abelian $G_2$-monopole (resp. Calabi-Yau monopole) with Dirac singularity along a calibrated cycle in the large mass limit, and we prove an energy identity for monopole bubbles.
