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arXiv · 1912.02431

Extrinsic geometry of the Gromoll-Meyer sphere

Chao Qian·Zizhou Tang·Wenjiao Yan
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Abstract

Among a family of 2-parameter left invariant metrics on Sp(2), we determine which have nonnegative sectional curvatures and which are Einstein. On the quotiente $\widetilde{N}^{11}=(Sp(2)\times S^4)/S^3$, we construct a homogeneous isoparametric foliation with isoparametric hypersurfaces diffeomorphic to Sp(2). Furthermore, on the quotiente $\widetilde{N}^{11}/S^3$, we construct a transnormal system with transnormal hypersurfaces diffeomorphic to the Gromoll-Meyer sphere $\Sigma^7$. Moreover, the induced metric on each hypersurface has positive Ricci curvature and quasi-positive sectional curvature simultaneously.

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Chao Qian, Zizhou Tang, Wenjiao Yan. 2019-12-05. Extrinsic geometry of the Gromoll-Meyer sphere. https://doi.org/10.1016/j.difgeo.2020.101638

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