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