THE MESON DISTRIBUTION AMPLITUDE OF EXCLUSIVE PROCESSES IN QCD

The behavior of the meson distribution amplitude is discussed through a phenomenological analysis of some exclusive processes in QCD.It is found that the pionicdistribution anplitirde at moderate energies is much broader than its asymptotic form and the broad distribution amplitude has to suppress the endpoint contribution to the process in order that the perturbative QCD contribution is dominant.In addition,a possible meson distribution amp1itude,which is a generalization of the harmonic oscillator model,is proposed.The results are compatible with experimental data.