Inserted: 7 nov 2018
Last Updated: 7 nov 2018
Given the pair of vector fields
where $(x,y,t)= (z,t)\in\R^3=\C\times\R$, we give a condition on a bounded domain $\Omega\subset\R^3$ which ensures that $\Omega$ is an $(\epsilon,\delta)$-domain for the Carnot-Carath\'eodory metric. We also analyze the Ahlfors regularity of the natural surface measure induced on $ \partial \Omega$ by the vector fields.