Restrictions of Heterotic G2 Structures and Instanton Connections

This chapter revisits recent results regarding the geometry and moduli of solutions of the heterotic string on manifolds Y with a G 2 structure. In particular, such heterotic G 2 systems can be rephrased in terms of a differential Ď acting on a complex Ωˇ∗(Y,Q), where Ωˇ=T∗Y⊕End(TY)⊕End(V), and Ď is an appropriate projection of an exterior covariant derivative D which satisfies an instanton condition. The infinitesimal moduli are further parametrized by the first cohomology HDˇ1(Y,Q). The chapter proceeds to restrict this system to manifolds X with an SU(3) structure corresponding to supersymmetric compactifications to four-dimensional Minkowski space, often referred to as Strominger–Hull solutions. In doing so, the chapter derives a new result: the Strominger–Hull system is equivalent to a particular holomorphic Yang–Mills covariant derivative on Q|X=T∗X⊕End(TX)⊕End(V).