Foliation by area-constrained willmore spheres near a nondegenerate critical point of the scalar curvature

Let (M, g) be a three-dimensional Riemannian manifold. The goal of the paper is to show that if P₀ ∈ M is a nondegenerate critical point of the scalar curvature, then a neighborhood of P₀ is foliated by area-constrained Willmore spheres. Such a foliation is unique among foliations by area-constrained Willmore spheres having Willmore energy less than 32π; moreover, it is regular in the sense that a suitable rescaling smoothly converges to a round sphere in the Euclidean three-dimensional space. We also establish generic multiplicity of foliations and the 1st multiplicity result for area-constrained Willmore spheres with prescribed (small) area in a closed Riemannian manifold. The topic has strict links with the Hawking mass.