On the rigidity of special and exceptional geometries with torsion a closed $3$-form
This paper establishes that Riemannian manifolds admitting a connection with closed, covariantly constant torsion decompose locally into a product of a semisimple Lie group and a torsion-free manifold, a result used to simplify proofs for special geometries like KT and HKT manifolds and to fully characterize the geometry of complete, simply connected , , and compact 8-dimensional HKT manifolds under these conditions.