ρD^*D^* vertex from QCD sum rules

Abstract

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

9 pages, 6 eps figures