$C^\infty$ rectifiability of stationary varifolds
Camillo Brena, Camillo De Lellis, Federico Franceschini
TL;DR
The paper proves that the support of any stationary $m$-dimensional integral rectifiable varifold in an open set $U\subset \mathbb{R}^{m+n}$ is $C^{\infty}$ rectifiable, i.e., covered up to $H^m$-null sets by countably many $C^{\infty}$ $m$-graphs. The authors innovate by replacing the classical best-approximating plane with a best-approximating minimal surface, establishing a decay lemma that drives $L^2$-distance contraction across scales. They develop a multivalued Lipschitz approximation on the normal bundle and a generalized tilt-excess inequality, together with elliptic regularization and Whitney-type arguments, to obtain $C^{\infty}$ rectifiability from quantitative excess decay. The results connect geometric measure theory with minimal-surface PDE techniques, yielding a robust route to higher-regularity structure of stationary varifolds and a framework potentially applicable to broader regularity problems in calibrated geometry and variational theory.
Abstract
In this paper we prove that, for every integers $m\geq 2$ and $n\geq 1$, the support of any stationary $m$-dimensional integer rectifiable varifold $V$ in an open set $U\subset \mathbb R^{m+n}$ is $C^\infty$ rectifiable, namely it can be covered, up to an $H^m$-null set, with countably many $C^\infty$ $m$-dimensional graphs.
