3 papers
math.DG2026
A characterization of complex projective space via the Calabi curvature operator
Hasan M. El-Hasan, Xiaolong Li, Jan Nienhaus +3
We prove a Tachibana-type result for Kähler-Einstein manifolds isolating complex projective space based on its Calabi curvature operator. The proof uses a new Bochner formula expre…
math.DG2025
Vanishing theorems for Hodge numbers and the Calabi curvature operator
Kyle Broder, Jan Nienhaus, Peter Petersen +2
It is shown that a compact -dimensional Kähler manifold with -positive Calabi curvature operator has the rational cohomology of complex projective space. For even…
math.DG2024
Einstein metrics on the Ten-Sphere
Jan Nienhaus, Matthias Wink
We prove the existence of three non-round, non-isometric Einstein metrics with positive scalar curvature on the sphere Previously, the only even-dimensional spheres known…