Pseudo-Riemannian VSI spaces
arXiv:1008.2838 · doi:10.1088/0264-9381/28/1/015008
Abstract
In this paper we consider pseudo-Riemannian spaces of arbitrary signature for which all of their polynomial curvature invariants vanish (VSI spaces). We discuss an algebraic classification of pseudo-Riemannian spaces in terms of the boost weight decomposition and define the - and -properties, and show that if the curvature tensors of the space possess the -property then it is a VSI space. We then use this result to construct a set of metrics that are VSI. All of the VSI spaces constructed possess a geodesic, expansion-free, shear-free, and twist-free null-congruence. We also discuss the related Walker metrics.
14 pages