Smooth approximations for constant-mean-curvature hypersurfaces with isolated singularities
Costante Bellettini, Konstantinos Leskas
TL;DR
The paper develops local smoothing results for constant-mean-curvature (CMC) hypersurfaces with isolated singularities under a regular tangent cone. Using the prescribed-mean-curvature functional $J_ extlambda$ on finite-perimeter sets, it proves the existence of smooth CMC hypersurfaces $T_j$ with mean curvature $ extlambda$ that converge to the original boundary $ar{igtriangleup}^* E$ in multiple senses, with $T_j=ar{igtriangleup}^* E_j$ and $E_j o E$. In ambient dimension $8$ the cone regularity is automatic, while for higher dimensions a regular tangent cone is assumed; a singular maximum principle for CMC hypersurfaces and a detailed Jacobi-operator analysis on cones underpin the approximation. The work extends Hardt--Simon-type results to the CMC Plateau problem and provides a robust framework for smoothing singularities in geometric variational problems, with implications for geometric constructions in high dimensions. The methods combine variational minimisation, blow-up analysis, cone stability, and foliation techniques to achieve strong convergence and regularity results.
Abstract
We consider a CMC hypersurface with an isolated singular point at which the tangent cone is regular, and such that, in a neighbourhood of said point, the hypersurface is the boundary of a Caccioppoli set that minimises the standard prescribed-mean-curvature functional. We prove that in a ball centred at the singularity there exists a sequence of smooth CMC hypersurfaces, with the same prescribed mean curvature, that converge to the given one. Moreover, these hypersurfaces arise as boundaries of minimisers. In ambient dimension $8$ the condition on the cone is redundant. (When the mean curvature vanishes identically, the result is the well-known Hardt--Simon approximation theorem.)
