Conformally Invariant Powers of the Laplacian, I: Existence
C. Robin Graham, Ralph Jenne, LIONEL J. MASON, George A. J. Sparling · Journal of the London Mathematical Society · 1992
A geometric derivation is given of a family of scalar conformally invariant differential operators on conformal densities with leading part a power of the Laplacian. The derivation produces an operator for each positive integral power in odd dimensions, but only for a finite range of powers in even dimensions. The operators are derived from the Laplacian in the ambient metric of Fefferman and Graham via extension.