Explicit ambient metrics and holonomy
arXiv:1501.00852 · doi:10.4310/jdg/1580526015
Abstract
We present three large classes of examples of conformal structures for which the equations for the Fefferman-Graham ambient metric to be Ricci-flat are linear PDEs, which we solve explicitly. These explicit solutions enable us to discuss the holonomy of the corresponding ambient metrics. Our examples include conformal pp-waves and, more importantly, conformal structures that are defined by generic rank 2 and 3 distributions in respective dimensions 5 and 6. The corresponding explicit Fefferman-Graham ambient metrics provide a large class of metrics with holonomy equal to the exceptional non-compact Lie group as well as ambient metrics with holonomy contained in .
30 pages; in Section 4 of v2 the results about ambient metrics for Bryant's conformal structures are significantly generalized