On constant mean curvature surfaces in the Heisenberg group
Dmitry Berdinsky
TL;DR
This work analyzes constant mean curvature surfaces in the 3D Heisenberg group ${\mathrm Nil}$ with Thurston geometry, using the Weierstrass representation and the Abresch--Rosenberg differential. The authors show that near non--umbilic points, a CMC surface with mean curvature $H$ is encoded by a complex potential $v$ solving the sinh--Gordon equation $\Delta v+8\sinh 2v=0$ together with a first--order constraint that ties the imaginary part of $v$ to its real part via spatial derivatives; for $H=0$ (minimal surfaces) an additional constraint $\operatorname{Re}(e^v)=0$ arises. The paper derives the Gauss--Weingarten equations and the holomorphicity of $Bdz^2$, and then establishes a Reality Condition linking the Dirac potential to the geometry, providing a framework for constructing CMC surfaces in ${\mathrm Nil}$ through soliton methods. This approach parallels Euclidean methods (e.g., Lamb's ansatz) and opens a path to explicit immersions of CMC surfaces in Nil via integrable systems techniques.
Abstract
We study constant mean curvature surfaces in the three-dimensional Heisenberg group. We prove that a constant mean curvature surface in a neighborhood of non-umbilic point is described by some solution of a sinh-Gordon equation subject to a first order differential constraint.
