A nonlinear Liouville theorem for fractional equations in the Heisenberg group

We establish a Liouville-type theorem for a subcritical nonlinear problem, involving a fractional power of the sub-Laplacian in the Heisenberg group. To prove our result we will use the local realization of fractional CR covariant operators, which can be constructed as the Dirichlet-to-Neumann operator of a degenerate elliptic equation in the spirit of Caffarelli and Silvestre [8], as established in [15]. The main tools in our proof are the CR inversion and the moving plane method, applied to the solution of the lifted problem in the half-space Hn×R+Hn×R+.