English

Espace de twisteurs d'une variete presque hermitienne de dimension 6

Differential Geometry 2007-05-23 v3

Abstract

We consider the reduced twistor space ZZ of an almost Hermitian manifold MM, after O'Brian and Rawnsley (Ann. Global Anal. Geom., 1985). We concentrate on dimension 6. This space has a natural almost complex structure J\mathcal J associated to the canonical Hermitian connection. A necessary condition for the integrability of J\mathcal J on ZZ is that the manifold belongs to the class W1W4W_1 \oplus W_4 of Gray, Hervella. In a second part, we then show that the almost Hermitian manifolds of type W1W4W_1 \oplus W_4 are all locally conformally nearly K\"{a}hler in dimension 6. Finally, J\mathcal J is integrable if and only if MM is locally conformal to the sphere S6S^6 or to a Bochner-flat K\"{a}hler manifold.

Keywords

Cite

@article{arxiv.math/0503150,
  title  = {Espace de twisteurs d'une variete presque hermitienne de dimension 6},
  author = {Jean-Baptiste Butruille},
  journal= {arXiv preprint arXiv:math/0503150},
  year   = {2007}
}

Comments

In french. Version 2. The paper has been abbreviated from 38 pages to 30. The proof of the actual lemma 5.2 has been precised. Three references were added : [3], [7] and mostly [9] (Cleyton, Ivanov, math.DG/0607487 : the authors completed our theorem 1 by proving that a 6-dimensional almost Hermitian manifold is locally conformally nearly K\"{a}hler if and only if it is globally conformally nearly K\"{a}hler)