Contact 5-manifolds with SU(2)-structure

Abstract

We consider 5-manifolds with a contact form arising from a hypo structure, which we call \emph{hypo-contact}. We provide conditions which imply that there exists such a structure on an oriented hypersurface of a 6-manifold with a half-flat SU(3)-structure. For half-flat manifolds with a Killing vector field $X$ preserving the SU(3)-structure we study the geometry of the orbits space. Moreover, we describe the solvable Lie algebras admitting a \emph{hypo-contact} structure. This allows us exhibit examples of Sasakian $η$-Einstein manifolds, as well as to prove that such structures give rise to new metrics with holonomy SU(3) and to new metrics with holonomy $G_2$.

23 pages, to be published in Q. J. Math