Willmore-type inequality in unbounded convex sets

Abstract

In this paper we prove the following Willmore-type inequality: On an unbounded closed convex set $K\subset\mathbb{R}^{n+1}$ $(n\ge 2)$, for any embedded hypersurface $\Sigma\subset K$ with boundary $\partial\Sigma\subset \partial K$ satisfying a certain contact angle condition, there holds $$\frac1{n+1}\int_{\Sigma}\vert{H}\vert^n{\rm d}A\ge{\rm AVR}(K)\vert\mathbb{B}^{n+1}\vert.$$ Moreover, equality holds if and only if $\Sigma$ is a part of a sphere and $K\setminus\Omega$ is a part of the solid cone determined by $\Sigma$. Here $\Omega$ is the bounded domain enclosed by $\Sigma$ and $\partial K$, $H$ is the normalized mean curvature of $\Sigma$, and ${\rm AVR}(K)$ is the asymptotic volume ratio of $K$. We also prove an anisotropic version of this Willmore-type inequality. As a special case, we obtain a Willmore-type inequality for anisotropic capillary hypersurfaces in a half-space.