How hard are the form factors in hadronic vertices with heavy mesons?

The NDΛc and ND∗Λc form factors are evaluated in a full QCD sum rule calculation. We study the double Borel sum rule for the three point function of one meson one nucleon and one Λc current up to order six in the operator product expansion. The double Borel transform is performed with respect to the nucleon and Λc momenta, and the form factor is evaluated as a function of the momentum Q2 of the heavy meson. These form factors are relevant to evaluate the charmonium absorption cross section by hadrons. Our results are compatible with constant form factors in these vertices.