Second pinching conjecture for closed minimal hypersurfaces

Let MnM^n with n>3n>3 be a closed minimal hypersurface in Sn+1(1)\mathbb{S}^{n+1}(1) with constant scalar curvature. Write SS for the squared norm of its second fundamental form.

Second pinching conjecture. If S>nS>n, then S2nS\geq 2n.

This conjecture asks whether 2n2n is the next possible pinching threshold after the known values 00 and nn, motivated by Cartan's isoparametric examples. Results under additional constancy assumptions on higher symmetric functions give weaker bounds, while the full assertion remains open.

Sources & referencesView supporting material

Primary source

Qintao Deng and Yunjia Kou, “Closed Minimal Hypersurfaces in S^5(1) with Constant Scalar and Gauss-Kronecker Curvatures”, arXiv:2607.06588 (2026).

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