The D∗Dπ form factor is evaluated in a QCD sum rule calculation for both D and π off-shell mesons. We study the Borel sum rule for the three-point function of one pseudoscalar, one axial and one vector meson currents. We find that the momentum dependence of the form factors is very different if the D or the π meson is off-shell, but they lead to the same coupling constant in the D∗Dπ vertex.
@article{arxiv.hep-ph/0109188,
title = {$D^*D\pi$ form factor revisited},
author = {F. S. Navarra and M. Nielsen and M. E. Bracco},
journal= {arXiv preprint arXiv:hep-ph/0109188},
year = {2009}
}