The intrinsic torsion of SU(3) and G_2 structures

We analyse the relationship between the components of the intrinsic torsion of an SU(3) structure on a 6-manifold and a G_2 structure on a 7-manifold. Various examples illustrate the type of SU(3) structure that can arise as a reduction of a metric with holonomy G_2.Comment: Proc. conf. Differential Geometry Valencia 200

SO(3)-Structures on 8-manifolds

We study Riemannian 8-manifolds with an infinitesimal action of SO(3) by which each tangent space breaks into irreducible spaces of dimensions 3 and 5. The relationship with quaternionic, almost product- and PSU-geometry is thoroughly explained using representation-theoretical arguments.Comment: 19 pages, 2 figure

Complex homothetic foliations on K\"ahler manifolds

We obtain a local classification of complex homothetic foliations on Kaehler manifolds by complex curves. This is used to construct almost Kaehler, Ricci-flat metrics subject to additional curvature properties.Comment: Final version, up to typos. To appear in BLM

Systems of symplectic forms on four-manifolds

We study almost Hermitian 4-manifolds with holonomy algebra, for the canonical Hermitian connection, of dimension at most one. We show how Riemannian 4-manifolds admitting five orthonormal symplectic forms fit therein and classify them. In this set-up we also fully describe almost Kaehler 4-manifolds.Comment: Final version, to appear in Annali di SNS.added thm. 5.

A landscape of non-supersymmetric AdS vacua on coset manifolds

We construct new families of non-supersymmetric sourceless type IIA AdS4 vacua on those coset manifolds that also admit supersymmetric solutions. We investigate the spectrum of left-invariant modes and find that most, but not all, of the vacua are stable under these fluctuations. Generically, there are also no massless moduli.Comment: 20 pages, 11 figures, v2: added some clarifications, references, v3: corrections addressing comments refere