CMC spheres in the Heisenberg group
  We study a family of spheres with constant mean curvature (CMC) in the Riemannian Heisenberg group $H^1$. These spheres are conjectured to be the isoperimetric sets of $H^1$. We prove several results supporting this conjecture. We also focus our attention on the sub-Riemannian limit. 
Valentina Franceschi, Francescopaolo Montefalcone, Roberto Monti
math.MG math.DG