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. 
Simon G. Chiossi, \'Oscar Maci\'a
math.DG