A Poincar\'e cone condition in the Poincar\'e group
Gradinaru and Ben Arous described the behavior of the Green function of a sub-elliptic diffusion. We adapt their proof in the general setting of an hypoelliptic diffusion and deduce a Wiener criterion and a Poincar\'e cone condition of thinness for a relativistic diffusion in the Poincar\'e group introduced by Dudley.