Spacetimes with all scalar curvature invariants in terms of the   Cosmological Constant
  In this letter we provide an invariant characterization for all spacetimes with all polynomial scalar invariants constructed from the Riemann tensor and its covariant derivatives vanishing except those zeroth order curvature invariants expressed as polynomials in $\Lambda$, the cosmological constant. Using this invariant description we provide explicit forms for the metric. 
David McNutt
gr-qc math.DG