2018/10/31 by Gu, Juanru, Lei, Li, Xu, Hongwei
#Differential Geometry (math.DG) #FOS: Mathematics
paper · doi:10.48550/arxiv.1810.13080
Let M be an n-dimensional closed hypersurface with constant mean curvature and constant scalar curvature in an unit sphere. Denote by H and S the mean curvature and the squared length of the second fundamental form respectively. We prove that if S > α(n, H), where n≥ 4 and H≠ 0, then S > α(n, H) + Bn(n H2)/(n - 1). Here α(n, H) = n + (n3)/(2 (n - 1)) H2 - (n (n - 2))/(2 (n - 1))√(n2 H4 + 4 (n - 1) H2), Bn=(1)/(5) for 4≤ n ≤ 20, and Bn=(49)/(250) for n>20. Moreover, we obtain a gap theorem for complete hypersurfaces with constant mean curvature and constant scalar curvature in space forms.