The semileptonic exclusive B- and D-decays on the light-front

We present a comprehensive account of a relativistic quark model on the light front which gives the form factors of weak hadronic currents among heavy pseudoscalar and vector mesons in the complete kinematic region 0 ≤ q2 ≤ qmax2. For the numerical investigations of the B → D∗lνl, B → ϱlνl, D → K∗lνl and D → ϱlνl semileptonic decays equal time wave functions using the updated values of the ISGW model are adopted. From the available experimental information on branching fractions BR(B → D∗lνl) and BR(B → ϱlνl) the CKM parameters |Vcb| and |Vub| are estimated to be |Vcb| = 0.036 ± 0.002, |Vub| = 0.0033 ± 0.0005. It is shown that the q2 distribution for the decay B → D∗ℓνℓ will allow for an accurate test of the value of |Vcb|. The model is compared to the experimental data, QCD sum rules and lattice calculations.