A $σ$-homothetic uniqueness of the critical catenoid
Iury Domingos, Roney Santos, Feliciano Vitório
TL;DR
The paper addresses rigidity of free boundary minimal annuli in the unit ball that are $\sigma$-homothetic to the critical catenoid. It derives a differential system for the conformal factor between two free boundary minimal annuli, showing that $\Delta\varphi = (1 - e^{C - 2\varphi})K$ on $\Sigma$ with $\partial_\nu\varphi = e^{\varphi}$ on $\partial\Sigma$, and relates Gaussian curvatures via $e^{2\varphi}\bar K = K - \Delta\varphi$, yielding $4\varphi = C + \log(\bar K^{-1}K)$. The main result shows that if an annulus conformal to the critical catenoid has $\varphi$ constant on at least one boundary component, it is congruent to the critical catenoid; more generally, any free boundary annulus $\sigma$-homothetic to the critical catenoid is isometric to it. This advances rigidity results for free boundary minimal surfaces in $B^3$ and ties into the $\sigma$-homothety framework examined by Fraser–Schoen.
Abstract
We prove a uniqueness result for free boundary minimal annuli in the unit Euclidean three-ball that are $σ$-homothetic to the critical catenoid.
