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arXiv 0901.2261math.DGgr-qchep-thmath-phmath.MP
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与Kahler共形的四维空间

Four--Dimensional Metrics Conformal to Kahler

Maciej Dunajski, Paul Tod

摘要:

本文给出了四维黎曼度量$(M, g)$局部共形于Kähler的一些必要条件。若共形曲率是非反自对偶的,则自对偶Weyl旋量必须是代数型$D$,并满足一个简单的一阶共形不变条件,这是共形类中存在Kähler度量的充要条件.在反自对偶情形下,我们建立了$M$上自然秩10向量丛上的共形类Kähler度量与某个联络的非零平行截面之间的一一对应.我们使用这个特性来提供ASD指标的例子,这是不符合凯勒。我们建立了一个链接之间的'共形凯勒条件'在第四个维度和度量化的投影结构在第二个维度。曲面$U$上的射影结构是可度量化的当且仅当$M=TU$上的诱导(2,2)共形结构允许Kähler度量或仿Kähler度量.

英文摘要:

We derive some necessary conditions on a Riemannian metric $(M, g)$ in four dimensions for it to be locally conformal to Kähler. If the conformal curvature is non anti--self--dual, the self--dual Weyl spinor must be of algebraic type $D$ and satisfy a simple first order conformally invariant condition which is necessary and sufficient for the existence of a Kähler metric in the conformal class. In the anti--self--dual case we establish a one to one correspondence between Kähler metrics in the conformal class and non--zero parallel sections of a certain connection on a natural rank ten vector bundle over $M$. We use this characterisation to provide examples of ASD metrics which are not conformal to Kähler. We establish a link between the `conformal to Kähler condition' in dimension four and the metrisability of projective structures in dimension two. A projective structure on a surface $U$ is metrisable if and only if the induced (2, 2) conformal structure on $M=TU$ admits a Kähler metric or a para-Kähler metric.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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