WEAK DECAY FORM-FACTORS OF HEAVY PSEUDOSCALAR MESONS WITHIN A LIGHT-FRONT CONSTITUENT QUARK-MODEL

The transition form factors describing the semileptonic decays of heav y pseudoscalar mesons are investigated within a relativistic constitue nt quark model formulated on the light-front. For the first time the f orm factors are calculated in the whole accessible kinematical region, adopting meson wave functions derived from various effective <q(q)ove r bar> interactions able to describe the meson mass spectra. It is sho wn that the decay rates of the B --> Dl nu(l), D --> Kl nu(l) and D -- > pi l nu(l) weak decays are mainly governed by the effects of the con finement scale, whereas the B --> pi l nu(l) decay rate is sensitive t o the high-momentum components generated in the meson wave functions b y the effective one-gluon-exchange interaction. Our results are consis tent with available experimental data and predictions of lattice QCD c alculations and QCD sum rules.