Large‑mass monopoles concentrate energy on calibrated three‑codimension shapes and become abelian away from them
This paper studies what happens to certain field configurations called monopoles when their mass grows very large on special geometric spaces known as asymptotically conical G2‑manifolds and Calabi–Yau three‑folds. Monopoles here are pairs of a gauge connection and a Higgs field with structure group SU(2) or SO(3). The main finding is that, after rescaling by the mass, the energy of these monopoles concentrates on a compact, calibrated geometric cycle T of codimension three. Quantitatively, two different mass‑renormalized energy measures converge to the same limit 8π‖T‖, so the two independent compactness theories in the literature pick out the same calibrated object T as the place where energy accumulates.
To reach this result the authors place several earlier analytic inputs into a common framework for so‑called Θ‑monopoles. They combine asymptotic results for monopoles on asymptotically conical spaces, a variational compactness theorem of Parise–Pigati–Stern, and a singular abelian compactness theory of Y. Li. With these tools they show that the variational inequalities are saturated and identify the two previously separate limiting currents (the geometric objects that record energy concentration) as one calibrated integral cycle T. In short, different approaches to the large‑mass limit agree and produce the same geometric concentration.
Beyond identifying T, the paper analyzes finer structure. Let S be the support of T, Z the limiting location of Higgs zeros (the points where the Higgs field vanishes in the limit), and C the limiting nonabelian locus where curvature concentrates. The authors prove the set inclusions S ⊂ Z ⊂ C and the precise identity C = S ∪ O, where O is a closed ‘‘obstruction’’ set that measures failure of a local monotonicity property. In practical terms, away from the set C the monopoles “abelianize”: the nonabelian gauge structure simplifies to an abelian one, transverse fields decay, and corrected longitudinal curvatures converge smoothly to satisfy linear Hodge equations up to small errors.