Form factors of meson decays in constituent quark model
  Meson decays are considered within the constituent quark model, making use of the dispersion formulation of the model: Starting with spacelike momentum transfers $q$, meson transition form factors are expressed as relativistic invariant double spectral representations over the invariant masses of the initial and final $Q\bar Q$ pairs. The form factors at timelike momentum transfers are obtained by performing the analytical continuation in $q^2$. As a result, the form factors both in the scattering and decay regions are expressed through the light--cone wave functions of the initial and final hadrons. The constituent quark transition form factor is briefly discussed. 
D. Melikhov