Umbilicity and characterization of Pansu spheres in the Heisenberg group
arXiv:1406.2444
Abstract
For we define a notion of umbilicity for hypersurfaces in the Heisenberg group . We classify umbilic hypersurfaces in some cases, and prove that Pansu spheres are the only umbilic spheres with positive constant (or horizontal)-mean curvature in up to Heisenberg translations.
32 pages, 2 figures; in Crelle's journal, 2015