Embeddedness of min–max CMC hypersurfaces in manifolds with positive Ricci curvature

Abstract

We prove that on a compact Riemannian manifold of dimension 3 or higher, with positive Ricci curvature, the Allen–Cahn min–max scheme in Bellettini and Wickramasekera (The Inhomogeneous Allen–Cahn Equation and the Existence of Prescribed-Mean-Curvature Hypersurfaces, 2020), with prescribing function taken to be a non-zero constant \(\lambda \), produces an embedded hypersurface of constant mean curvature \(\lambda \) (\(\lambda \)-CMC). More precisely, we prove that the interface arising from said min–max contains no even-multiplicity minimal hypersurface and no quasi-embedded points (both of these occurrences are in principle possible in the conclusions of Bellettini and Wickramasekera, 2020). The immediate geometric corollary is the existence (in ambient manifolds as above) of embedded, closed \(\lambda \)-CMC hypersurfaces (with Morse index 1) for any prescribed non-zero constant \(\lambda \), with the expected singular set when the ambient dimension is 8 or higher.