J/psi D*D* vertex from QCD sum rules

Abstract

We calculated the strong form factor and coupling constant for the $J/\psi D^{\ast }{D}^{\ast }$ vertex in a QCD sum rule calculation. We performed a double Borel sum rule for the three point correlation function of vertex considering both $J/\psi$ and $D^{\ast }$ mesons off--shell. The form factors obtained are very different, but they give the same coupling constant.

Comments: 7 pages and 4 figures, replaced version accepted for publication in Phys. Lett. B