Improved convergence theorems for bubble clusters. II. The three-dimensional case

Abstract

Given a sequence $\{{\mathcal{E}}_k{\}}_k$ of almost-minimizing clusters in ${\mathbb{R}}^3$ which converges in $L^1$ to a limit cluster $\mathcal{E}$ we prove the existence of $C^{1,\alpha }$-diffeomorphisms $f_k$ between $\partial \mathcal{E}$ and $\partial {\mathcal{E}}_k$ which converge in $C^1$ to the identity. Each of these boundaries is divided into $C^{1,\alpha }$-surfaces of regular points, $C^{1,\alpha }$-curves of points of type $Y$ (where the boundary blows-up to three half-spaces meeting along a line at 120 degree) and isolated points of type $T$ (where the boundary blows up to the two-dimensional cone over a one-dimensional regular tetrahedron). The diffeomorphisms $f_k$ are compatible with this decomposition, in the sense that they bring regular points into regular points and singular points of a kind into singular points of the same kind. They are almost-normal, meaning that at fixed distance from the set of singular points each $f_k$ is a normal deformation of $\partial \mathcal{E}$, and at fixed distance from the points of type $T$, $f_k$ is a normal deformation of the set of points of type $Y$. Finally, the tangential displacements are quantitatively controlled by the normal displacements. This improved convergence theorem is then used in the study of isoperimetric clusters in ${\mathbb{R}}^3$.

35 pages