A remark on conformal $\SU(p,q)$-holonomy
arXiv:math/0604393
Abstract
If the conformal holonomy group of a simply connected space with conformal structure of signature is reduced to $\U(p,q)$ then the conformal holonomy is already contained in the special unitary group $\SU(p,q)$. We present two different proofs of this statement, one using conformal tractor calculus and an alternative proof using Sparling's characterisation of Fefferman metrics.
14 pages