Orthogonal almost complex structure and its Nijenhuis tensor

Fuente: arXiv
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Hauptverfasser: Tang, Zizhou, Yan, Wenjiao
Format: Preprint
Veröffentlicht: 2024
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author Tang, Zizhou
Yan, Wenjiao
author_facet Tang, Zizhou
Yan, Wenjiao
contents In this paper, we demonstrate that on an almost Hermitian manifold $(M^{2n}, J, ds^2)$, a 2-form $φ=S^*Φ$, the pulling back of the Kähler form $Φ$ on the twistor bundle over $M^{2n}$, is non-degenerate if the squared norm $|N|^2$ of the Nijenhuis tensor is less than $\frac{64}{5}$ when $n\geq 3$ or less than $16$ when $n=2$. As a corollary, there exists no orthogonal almost complex structure on the standard sphere $(S^6, ds_0^2)$ with $|N|^2<\frac{64}{5}$ everywhere.
format Preprint
id arxiv_https___arxiv_org_abs_2401_14213
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Orthogonal almost complex structure and its Nijenhuis tensor
Tang, Zizhou
Yan, Wenjiao
Differential Geometry
Complex Variables
In this paper, we demonstrate that on an almost Hermitian manifold $(M^{2n}, J, ds^2)$, a 2-form $φ=S^*Φ$, the pulling back of the Kähler form $Φ$ on the twistor bundle over $M^{2n}$, is non-degenerate if the squared norm $|N|^2$ of the Nijenhuis tensor is less than $\frac{64}{5}$ when $n\geq 3$ or less than $16$ when $n=2$. As a corollary, there exists no orthogonal almost complex structure on the standard sphere $(S^6, ds_0^2)$ with $|N|^2<\frac{64}{5}$ everywhere.
title Orthogonal almost complex structure and its Nijenhuis tensor
topic Differential Geometry
Complex Variables
url https://arxiv.org/abs/2401.14213