ON THE COUPLING OF HEAVY MESONS TO PIONS IN QCD

We compute the strong coupling constant g(P)(P pi), With P and P* res pectively pseudoscalar and vector heavy mesons by using the QCD sum ru les approach. Our computation is based on the evaluation of the time o rdered product of currents between the vacuum and the soft pion state. The so-called parasitic terms are taken into account and give a contr ibution to the sum rule of the same order of the lowest lying state, w hile higher dimension non perturbative terms have small numerical effe cts. The infinite heavy quark mass limit is also examined.