Optimal regularity for minimizers of the prescribed mean curvature functional over isotopies
Lorenzo Sarnataro, Douglas Stryker
TL;DR
This work develops a sharp regularity theory for minimizers of the $h$-prescribed mean curvature functional $\mathcal{A}^h$ over isotopy classes, achieving optimal $C^{1,1}$ regularity by extending the AS and MSY strategies to the $\mathcal{A}^h$ setting. It introduces a robust machinery—including fill-ins, resolution of overlaps, replacement, and the $n$-membrane framework—to control topology, obtain strong compactness, and upgrade regularity via free boundary techniques (WZ_multiple). A central outcome is a min-max existence result in the round $S^3$ showing that, for an open dense set of prescribing functions with $\|h\|_{L^{\infty}}\le 0.547$, there exists an embedded sphere with prescribed mean curvature; the method yields explicit density/mass controls and provides sharp regularity up to $C^{1,1}$. The results thus deliver a quantitative, topologically controlled existence theory for prescribed mean curvature spheres in $S^3$, with potential extensions to more general metrics and curvature regimes. Key innovations include the precise $C^{1,1}$ regularity theory, the gamma-reduction paradigm for isotopy minimization, and a min-max framework that tightly couples area, volume, and mean curvature through controlled variational and geometric-analytic tools.
Abstract
We prove the optimal $C^{1,1}$ regularity for minimizers of the prescribed mean curvature functional over isotopy classes. As an application, we find an embedded sphere of prescribed mean curvature in the round 3-sphere for an open dense set of prescribing functions with $L^{\infty}$ norm at most 0.547.
