Index-one capillary minimal hypersurfaces in ${\mathbb{R}}_{+}^n$

We classify complete, two-sided, properly embedded capillary minimal surfaces with nonempty boundary and Morse index one in ${\mathbb{R}}_{+}^3$. More precisely, if the boundary is compact, these surfaces are catenoid truncations; if the boundary is noncompact, they are capillary hairpin surfaces. The classification extends to higher dimensions under extrinsic Euclidean volume growth and Wang–Zhang’s dimension and angle conditions.