rho D^*D^* vertex from QCD sum rules

We calculate the form factors and the coupling constant in the $rho D^* D^*$ vertex in the framework of QCD sum rules. We evaluate the three point correlation functions of the vertex considering both $rho$ and $D^*$ mesons off--shell. The form factors obtained are very different but give the same coupling constant: $g_{rho D^* D^*} = 6.6 pm 0.31$. This number is 50% larger than what we would expect from SU(4) estimates.