Hypersurfaces of sn+1 with two distinct principal curvatures

Abstract

The aim of this paper is to prove that the Ricci curvature RicM of a complete hypersurface Mn, n≥3, of the Euclidean sphere Sn+1, with two distinct principal curvatures of multiplicity 1 and n−1, satisfies supRicM≥inff(H), for a function\, f depending only on n and the mean curvature H. Supposing in addition that Mn is compact, we will show that the equality occurs if and only if H is constant and Mn is isometric to a Clifford torus Sn−1(r)×S1(1−r2−−−−−√).