We show that the conformally invariant fractional powers of the sub-Laplacian
on the Heisenberg group are given in terms of the scattering operator for an extension
problem to the Siegel upper halfspace. Remarkably, this extension problem is di erent
from the one studied, among others, by Ca arelli and Silvestre.
CitacióFrank, Rupert L. [et al.]. An extension problem for the CR fractional Laplacian. "Advances in mathematics", 01 Gener 2015, vol. 270, núm. --, p. 97-137.