“…Fractional CR covariant operators of order 2γ, γ ∈ R, may be defined from scattering theory on a Kähler-Einstein manifold X [21,45,40,33], they are pseudodifferential operators whose principal symbol agrees with the pure fractional powers of the CR sub-Laplacian (−∆ b ) γ on the boundary M = ∂X . In the particular case of the Heisenberg group H n , they are simply the intertwining operators on the CR sphere calculated in [8,51,9] using classical representation theory tools.…”