The index of cubic focal manifolds

Fuente: arXiv
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Main Authors: Rauchenberger, Niklas, Semmelmann, Uwe
Format: Preprint
Published: 2026
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author Rauchenberger, Niklas
Semmelmann, Uwe
author_facet Rauchenberger, Niklas
Semmelmann, Uwe
contents We calculate the index and nullity of the three orientable focal manifolds of isoparametric hypersurfaces in spheres with three distinct principal curvatures. It turns out that the index is equal to the dimension of the ambient Euclidean space and the nullity is completely determined by the normal part of Killing vector fields of the ambient sphere. In that sense, the Veronese embeddings of the projective planes are as stable as possible for non totally geodesic submanifolds of the sphere.
format Preprint
id arxiv_https___arxiv_org_abs_2604_09802
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle The index of cubic focal manifolds
Rauchenberger, Niklas
Semmelmann, Uwe
Differential Geometry
53A10, 53C35
We calculate the index and nullity of the three orientable focal manifolds of isoparametric hypersurfaces in spheres with three distinct principal curvatures. It turns out that the index is equal to the dimension of the ambient Euclidean space and the nullity is completely determined by the normal part of Killing vector fields of the ambient sphere. In that sense, the Veronese embeddings of the projective planes are as stable as possible for non totally geodesic submanifolds of the sphere.
title The index of cubic focal manifolds
topic Differential Geometry
53A10, 53C35
url https://arxiv.org/abs/2604.09802